From 8610d90838ba9fb3fff236f4cba6e41ce58bc980 Mon Sep 17 00:00:00 2001
From: Luke Parker <10430890+Hona@users.noreply.github.com>
Date: Sat, 15 Aug 2026 15:57:46 +1000
Subject: [PATCH] fix(app): project sent messages through inbox events (#42714)

---
 .../prompt-input/build-prompt-request.test.ts | 321 ++++++++++
 .../prompt-input/build-prompt-request.ts      | 115 ++++
 .../prompt-input/build-request-parts.test.ts  | 396 ------------
 .../prompt-input/build-request-parts.ts       | 216 -------
 .../components/prompt-input/submit.test.ts    | 101 +++-
 .../app/src/components/prompt-input/submit.ts |  86 +--
 packages/app/src/context/directory-sync.ts    |  38 +-
 packages/app/src/context/file/path.test.ts    |   2 +-
 .../context/server-session-v2-reducer.test.ts |  26 +
 .../src/context/server-session-v2-reducer.ts  |  17 +-
 .../app/src/context/server-session.test.ts    | 569 ++++++++++--------
 packages/app/src/context/server-session.ts    | 501 ++++++++-------
 packages/app/src/context/server-sync.tsx      |   5 +-
 .../app/src/context/sync-optimistic.test.ts   | 137 -----
 packages/app/src/context/sync.tsx             | 108 ----
 15 files changed, 1140 insertions(+), 1498 deletions(-)
 create mode 100644 packages/app/src/components/prompt-input/build-prompt-request.test.ts
 create mode 100644 packages/app/src/components/prompt-input/build-prompt-request.ts
 delete mode 100644 packages/app/src/components/prompt-input/build-request-parts.test.ts
 delete mode 100644 packages/app/src/components/prompt-input/build-request-parts.ts
 delete mode 100644 packages/app/src/context/sync-optimistic.test.ts

diff --git a/packages/app/src/components/prompt-input/build-prompt-request.test.ts b/packages/app/src/components/prompt-input/build-prompt-request.test.ts
new file mode 100644
index 00000000000..58868bc3caa
--- /dev/null
+++ b/packages/app/src/components/prompt-input/build-prompt-request.test.ts
@@ -0,0 +1,321 @@
+import { describe, expect, test } from "bun:test"
+import type { Prompt } from "@/context/prompt"
+import { buildPromptRequest } from "./build-prompt-request"
+
+describe("buildPromptRequest", () => {
+  test("builds text, files, and agents from the prompt", () => {
+    const prompt: Prompt = [
+      { type: "text", content: "hello", start: 0, end: 5 },
+      {
+        type: "file",
+        path: "src/foo.ts",
+        content: "@src/foo.ts",
+        start: 5,
+        end: 16,
+        selection: { startLine: 4, startChar: 1, endLine: 6, endChar: 1 },
+      },
+      { type: "agent", name: "planner", content: "@planner", start: 16, end: 24 },
+    ]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [{ key: "ctx:1", type: "file", path: "src/bar.ts", comment: "check this" }],
+      images: [
+        { type: "image", id: "img_1", filename: "a.png", mime: "image/png", dataUrl: "data:image/png;base64,AAA" },
+      ],
+      text: "hello @src/foo.ts @planner",
+      sessionDirectory: "/repo",
+    })
+
+    expect(result.text).toContain("hello @src/foo.ts @planner")
+    expect(result.text).toContain("check this")
+    expect(result.displayText).toBe("hello @src/foo.ts @planner")
+    expect(result.comments).toMatchObject([{ path: "src/bar.ts", comment: "check this" }])
+    expect(result.agents).toEqual([{ name: "planner", mention: { start: 16, end: 24, text: "@planner" } }])
+    expect(result.files.some((file) => file.uri.startsWith("file:///repo/src/foo.ts"))).toBe(true)
+    expect(result.files.find((file) => file.uri.startsWith("file:///repo/src/foo.ts"))?.mention).toEqual({
+      start: 5,
+      end: 16,
+      text: "@src/foo.ts",
+    })
+  })
+
+  test("keeps multiple uploaded attachments in order", () => {
+    const result = buildPromptRequest({
+      prompt: [{ type: "text", content: "check these", start: 0, end: 11 }],
+      context: [],
+      images: [
+        { type: "image", id: "img_1", filename: "a.png", mime: "image/png", dataUrl: "data:image/png;base64,AAA" },
+        {
+          type: "image",
+          id: "img_2",
+          filename: "b.pdf",
+          mime: "application/pdf",
+          dataUrl: "data:application/pdf;base64,BBB",
+        },
+      ],
+      text: "check these",
+      sessionDirectory: "/repo",
+    })
+
+    const uploads = result.files.filter((file) => file.uri.startsWith("data:"))
+
+    expect(uploads).toHaveLength(2)
+    expect(uploads.map((file) => file.name)).toEqual(["a.png", "b.pdf"])
+  })
+
+  test("preserves an external attachment source path for the model", () => {
+    const result = buildPromptRequest({
+      prompt: [],
+      context: [],
+      images: [
+        {
+          type: "image",
+          id: "img_external",
+          filename: "opencode.global.dat",
+          sourcePath: "C:\\Users\\Luke\\AppData\\Roaming\\ai.opencode.desktop.beta\\opencode.global.dat",
+          mime: "text/plain",
+          dataUrl: "data:text/plain;base64,AAA",
+        },
+      ],
+      text: "inspect this",
+      sessionDirectory: "C:\\Repos\\sst\\opencode",
+    })
+
+    expect(result.files[0]?.name).toBe(
+      "C:\\Users\\Luke\\AppData\\Roaming\\ai.opencode.desktop.beta\\opencode.global.dat",
+    )
+  })
+
+  test("preserves reference aliases as directory files", () => {
+    const result = buildPromptRequest({
+      prompt: [
+        {
+          type: "file",
+          path: "/repo/../docs",
+          content: "@docs",
+          start: 0,
+          end: 5,
+          mime: "application/x-directory",
+          filename: "docs",
+        },
+      ],
+      context: [],
+      images: [],
+      text: "@docs",
+      sessionDirectory: "/repo/app",
+    })
+
+    expect(result.files[0]).toEqual({
+      uri: "file:///repo/../docs",
+      mime: "application/x-directory",
+      name: "docs",
+      mention: { start: 0, end: 5, text: "@docs" },
+    })
+  })
+
+  test("deduplicates context files when prompt already includes same path", () => {
+    const prompt: Prompt = [{ type: "file", path: "src/foo.ts", content: "@src/foo.ts", start: 0, end: 11 }]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [
+        { key: "ctx:dup", type: "file", path: "src/foo.ts" },
+        { key: "ctx:comment", type: "file", path: "src/foo.ts", comment: "focus here" },
+      ],
+      images: [],
+      text: "@src/foo.ts",
+      sessionDirectory: "/repo",
+    })
+
+    const fooFiles = result.files.filter((file) => file.uri.startsWith("file:///repo/src/foo.ts"))
+
+    expect(fooFiles).toHaveLength(2)
+    expect(result.text).toContain("focus here")
+  })
+
+  test("adds files for @mentions inside comment text", () => {
+    const result = buildPromptRequest({
+      prompt: [{ type: "text", content: "look", start: 0, end: 4 }],
+      context: [
+        {
+          key: "ctx:comment-mention",
+          type: "file",
+          path: "src/review.ts",
+          comment: "Compare with @src/shared.ts and @src/review.ts.",
+        },
+      ],
+      images: [],
+      text: "look",
+      sessionDirectory: "/repo",
+    })
+
+    expect(result.files).toHaveLength(2)
+    expect(result.files.some((file) => file.uri === "file:///repo/src/review.ts")).toBe(true)
+    expect(result.files.some((file) => file.uri === "file:///repo/src/shared.ts")).toBe(true)
+  })
+
+  test("handles Windows paths correctly (simulated on macOS)", () => {
+    const prompt: Prompt = [{ type: "file", path: "src\\foo.ts", content: "@src\\foo.ts", start: 0, end: 11 }]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [],
+      images: [],
+      text: "@src\\foo.ts",
+      sessionDirectory: "D:\\projects\\myapp", // Windows path
+    })
+
+    const file = result.files[0]
+    expect(file).toBeDefined()
+    // URL should be parseable
+    expect(() => new URL(file!.uri)).not.toThrow()
+    // Should not have encoded backslashes in wrong place
+    expect(file!.uri).not.toContain("%5C")
+    // Should have normalized to forward slashes
+    expect(file!.uri).toContain("/src/foo.ts")
+  })
+
+  test("handles Windows absolute path with special characters", () => {
+    const prompt: Prompt = [{ type: "file", path: "file#name.txt", content: "@file#name.txt", start: 0, end: 14 }]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [],
+      images: [],
+      text: "@file#name.txt",
+      sessionDirectory: "C:\\Users\\test\\Documents", // Windows path
+    })
+
+    const file = result.files[0]
+    expect(file).toBeDefined()
+    // URL should be parseable
+    expect(() => new URL(file!.uri)).not.toThrow()
+    // Special chars should be encoded
+    expect(file!.uri).toContain("file%23name.txt")
+    // Should have Windows drive letter properly encoded
+    expect(file!.uri).toMatch(/file:\/\/\/[A-Z]:/)
+  })
+
+  test("handles Linux absolute paths correctly", () => {
+    const prompt: Prompt = [{ type: "file", path: "src/app.ts", content: "@src/app.ts", start: 0, end: 10 }]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [],
+      images: [],
+      text: "@src/app.ts",
+      sessionDirectory: "/home/user/project",
+    })
+
+    expect(result.files[0]?.uri).toBe("file:///home/user/project/src/app.ts")
+  })
+
+  test("handles macOS paths correctly", () => {
+    const prompt: Prompt = [{ type: "file", path: "README.md", content: "@README.md", start: 0, end: 9 }]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [],
+      images: [],
+      text: "@README.md",
+      sessionDirectory: "/Users/kelvin/Projects/opencode",
+    })
+
+    expect(result.files[0]?.uri).toBe("file:///Users/kelvin/Projects/opencode/README.md")
+  })
+
+  test("handles context files with Windows paths", () => {
+    const result = buildPromptRequest({
+      prompt: [],
+      context: [
+        { key: "ctx:1", type: "file", path: "src\\utils\\helper.ts" },
+        { key: "ctx:2", type: "file", path: "test\\unit.test.ts", comment: "check tests" },
+      ],
+      images: [],
+      text: "test",
+      sessionDirectory: "D:\\workspace\\app",
+    })
+
+    expect(result.files).toHaveLength(2)
+
+    // All file URLs should be valid
+    result.files.forEach((file) => {
+      expect(() => new URL(file.uri)).not.toThrow()
+      expect(file.uri).not.toContain("%5C") // No encoded backslashes
+    })
+  })
+
+  test("handles absolute Windows paths (user manually specifies full path)", () => {
+    const prompt: Prompt = [
+      { type: "file", path: "D:\\other\\project\\file.ts", content: "@D:\\other\\project\\file.ts", start: 0, end: 25 },
+    ]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [],
+      images: [],
+      text: "@D:\\other\\project\\file.ts",
+      sessionDirectory: "C:\\current\\project",
+    })
+
+    const file = result.files[0]
+    expect(file).toBeDefined()
+    // Should handle absolute path that differs from sessionDirectory
+    expect(() => new URL(file!.uri)).not.toThrow()
+    expect(file!.uri).toContain("/D:/other/project/file.ts")
+  })
+
+  test("handles selection with query parameters on Windows", () => {
+    const prompt: Prompt = [
+      {
+        type: "file",
+        path: "src\\App.tsx",
+        content: "@src\\App.tsx",
+        start: 0,
+        end: 11,
+        selection: { startLine: 10, startChar: 0, endLine: 20, endChar: 5 },
+      },
+    ]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [],
+      images: [],
+      text: "@src\\App.tsx",
+      sessionDirectory: "C:\\project",
+    })
+
+    const file = result.files[0]
+    expect(file).toBeDefined()
+    // Should have query parameters
+    expect(file!.uri).toContain("?start=10&end=20")
+    // Should be valid URL
+    expect(() => new URL(file!.uri)).not.toThrow()
+    // Query params should parse correctly
+    const url = new URL(file!.uri)
+    expect(url.searchParams.get("start")).toBe("10")
+    expect(url.searchParams.get("end")).toBe("20")
+  })
+
+  test("handles file paths with dots and special segments on Windows", () => {
+    const prompt: Prompt = [
+      { type: "file", path: "..\\..\\shared\\util.ts", content: "@..\\..\\shared\\util.ts", start: 0, end: 21 },
+    ]
+
+    const result = buildPromptRequest({
+      prompt,
+      context: [],
+      images: [],
+      text: "@..\\..\\shared\\util.ts",
+      sessionDirectory: "C:\\projects\\myapp\\src",
+    })
+
+    const file = result.files[0]
+    expect(file).toBeDefined()
+    // Should be valid URL
+    expect(() => new URL(file!.uri)).not.toThrow()
+    // Should preserve .. segments (backend normalizes)
+    expect(file!.uri).toContain("/..")
+  })
+})
diff --git a/packages/app/src/components/prompt-input/build-prompt-request.ts b/packages/app/src/components/prompt-input/build-prompt-request.ts
new file mode 100644
index 00000000000..255b38a68f6
--- /dev/null
+++ b/packages/app/src/components/prompt-input/build-prompt-request.ts
@@ -0,0 +1,115 @@
+import { getFilename } from "@opencode-ai/core/util/path"
+import type { FileSelection } from "@/context/file"
+import { encodeFilePath } from "@/context/file/path"
+import type { AgentPart, FileAttachmentPart, ImageAttachmentPart, Prompt } from "@/context/prompt"
+import { formatCommentNote, type PromptComment } from "@/utils/comment-note"
+
+// Network fields feed both boundaries; display fields keep desktop-only rendering details in the local echo.
+type PromptRequest = {
+  text: string
+  displayText: string
+  files: { uri: string; mime: string; name?: string; mention?: { start: number; end: number; text: string } }[]
+  agents: { name: string; mention?: { start: number; end: number; text: string } }[]
+  comments: PromptComment[]
+}
+
+type ContextFile = {
+  key: string
+  type: "file"
+  path: string
+  selection?: FileSelection
+  comment?: string
+  commentID?: string
+  commentOrigin?: "review" | "file"
+  preview?: string
+}
+
+type BuildPromptRequestInput = {
+  prompt: Prompt
+  context: ContextFile[]
+  images: (Omit<ImageAttachmentPart, "blob"> & { dataUrl: string })[]
+  text: string
+  sessionDirectory: string
+}
+
+const absolute = (directory: string, path: string) => {
+  if (path.startsWith("/")) return path
+  if (/^[A-Za-z]:[\\/]/.test(path) || /^[A-Za-z]:$/.test(path)) return path
+  if (path.startsWith("\\\\") || path.startsWith("//")) return path
+  return `${directory.replace(/[\\/]+$/, "")}/${path}`
+}
+
+const fileQuery = (selection: FileSelection | undefined) =>
+  selection ? `?start=${selection.startLine}&end=${selection.endLine}` : ""
+
+const mention = /(^|[\s([{"'])@(\S+)/g
+
+const parseCommentMentions = (comment: string) => {
+  return Array.from(comment.matchAll(mention)).flatMap((match) => {
+    const path = (match[2] ?? "").replace(/[.,!?;:)}\]"']+$/, "")
+    if (!path) return []
+    return [path]
+  })
+}
+
+const isFileAttachment = (part: Prompt[number]): part is FileAttachmentPart => part.type === "file"
+const isAgentAttachment = (part: Prompt[number]): part is AgentPart => part.type === "agent"
+
+export function buildPromptRequest(input: BuildPromptRequestInput): PromptRequest {
+  const files = input.prompt.filter(isFileAttachment).map((attachment) => {
+    const path = absolute(input.sessionDirectory, attachment.path)
+    return {
+      uri: attachment.url ?? `file://${encodeFilePath(path)}${fileQuery(attachment.selection)}`,
+      mime: attachment.mime ?? "text/plain",
+      name: attachment.filename ?? getFilename(attachment.path),
+      mention: { start: attachment.start, end: attachment.end, text: attachment.content },
+    }
+  })
+
+  const agents = input.prompt.filter(isAgentAttachment).map((attachment) => ({
+    name: attachment.name,
+    mention: { start: attachment.start, end: attachment.end, text: attachment.content },
+  }))
+
+  const used = new Set(files.map((file) => file.uri))
+  const comments: PromptComment[] = []
+  const context = input.context.flatMap((item) => {
+    const path = absolute(input.sessionDirectory, item.path)
+    const uri = `file://${encodeFilePath(path)}${fileQuery(item.selection)}`
+    const comment = item.comment?.trim()
+    if (!comment && used.has(uri)) return []
+    used.add(uri)
+
+    const file = { uri, mime: "text/plain", name: getFilename(item.path) }
+    if (!comment) return [file]
+
+    comments.push({
+      path: item.path,
+      selection: item.selection,
+      comment,
+      preview: item.preview,
+      origin: item.commentOrigin,
+    })
+    const mentions = parseCommentMentions(comment).flatMap((path) => {
+      const uri = `file://${encodeFilePath(absolute(input.sessionDirectory, path))}`
+      if (used.has(uri)) return []
+      used.add(uri)
+      return [{ uri, mime: "text/plain", name: getFilename(path) }]
+    })
+    return [file, ...mentions]
+  })
+
+  const images = input.images.map((attachment) => ({
+    uri: attachment.dataUrl,
+    mime: attachment.mime,
+    name: attachment.sourcePath ?? attachment.filename,
+  }))
+
+  return {
+    text: [...(input.text.trim() ? [input.text] : []), ...comments.map(formatCommentNote)].join("\n"),
+    displayText: input.text,
+    files: [...files, ...context, ...images],
+    agents,
+    comments,
+  }
+}
diff --git a/packages/app/src/components/prompt-input/build-request-parts.test.ts b/packages/app/src/components/prompt-input/build-request-parts.test.ts
deleted file mode 100644
index ab84cb6eae8..00000000000
--- a/packages/app/src/components/prompt-input/build-request-parts.test.ts
+++ /dev/null
@@ -1,396 +0,0 @@
-import { describe, expect, test } from "bun:test"
-import type { Prompt } from "@/context/prompt"
-import { buildRequestParts } from "./build-request-parts"
-
-describe("buildRequestParts", () => {
-  test("builds typed request and optimistic parts without cast path", () => {
-    const prompt: Prompt = [
-      { type: "text", content: "hello", start: 0, end: 5 },
-      {
-        type: "file",
-        path: "src/foo.ts",
-        content: "@src/foo.ts",
-        start: 5,
-        end: 16,
-        selection: { startLine: 4, startChar: 1, endLine: 6, endChar: 1 },
-      },
-      { type: "agent", name: "planner", content: "@planner", start: 16, end: 24 },
-    ]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [{ key: "ctx:1", type: "file", path: "src/bar.ts", comment: "check this" }],
-      images: [
-        { type: "image", id: "img_1", filename: "a.png", mime: "image/png", dataUrl: "data:image/png;base64,AAA" },
-      ],
-      text: "hello @src/foo.ts @planner",
-      messageID: "msg_1",
-      sessionID: "ses_1",
-      sessionDirectory: "/repo",
-    })
-
-    expect(result.requestParts[0]?.type).toBe("text")
-    expect(result.requestParts.some((part) => part.type === "agent")).toBe(true)
-    expect(
-      result.requestParts.some((part) => part.type === "file" && part.url.startsWith("file:///repo/src/foo.ts")),
-    ).toBe(true)
-    expect(result.requestParts.some((part) => part.type === "text" && part.synthetic)).toBe(true)
-    expect(
-      result.requestParts.some(
-        (part) =>
-          part.type === "text" &&
-          part.synthetic &&
-          part.metadata?.opencodeComment &&
-          (part.metadata.opencodeComment as { comment?: string }).comment === "check this",
-      ),
-    ).toBe(true)
-
-    expect(result.optimisticParts).toHaveLength(result.requestParts.length)
-    expect(result.optimisticParts.every((part) => part.sessionID === "ses_1" && part.messageID === "msg_1")).toBe(true)
-  })
-
-  test("keeps multiple uploaded attachments in order", () => {
-    const result = buildRequestParts({
-      prompt: [{ type: "text", content: "check these", start: 0, end: 11 }],
-      context: [],
-      images: [
-        { type: "image", id: "img_1", filename: "a.png", mime: "image/png", dataUrl: "data:image/png;base64,AAA" },
-        {
-          type: "image",
-          id: "img_2",
-          filename: "b.pdf",
-          mime: "application/pdf",
-          dataUrl: "data:application/pdf;base64,BBB",
-        },
-      ],
-      text: "check these",
-      messageID: "msg_multi",
-      sessionID: "ses_multi",
-      sessionDirectory: "/repo",
-    })
-
-    const files = result.requestParts.filter((part) => part.type === "file" && part.url.startsWith("data:"))
-
-    expect(files).toHaveLength(2)
-    expect(files.map((part) => (part.type === "file" ? part.filename : ""))).toEqual(["a.png", "b.pdf"])
-  })
-
-  test("preserves an external attachment source path for the model", () => {
-    const result = buildRequestParts({
-      prompt: [],
-      context: [],
-      images: [
-        {
-          type: "image",
-          id: "img_external",
-          filename: "opencode.global.dat",
-          sourcePath: "C:\\Users\\Luke\\AppData\\Roaming\\ai.opencode.desktop.beta\\opencode.global.dat",
-          mime: "text/plain",
-          dataUrl: "data:text/plain;base64,AAA",
-        },
-      ],
-      text: "inspect this",
-      messageID: "msg_external",
-      sessionID: "ses_external",
-      sessionDirectory: "C:\\Repos\\sst\\opencode",
-    })
-
-    expect(result.requestParts.find((part) => part.type === "file")?.filename).toBe(
-      "C:\\Users\\Luke\\AppData\\Roaming\\ai.opencode.desktop.beta\\opencode.global.dat",
-    )
-  })
-
-  test("preserves reference aliases as directory file parts", () => {
-    const result = buildRequestParts({
-      prompt: [
-        {
-          type: "file",
-          path: "/repo/../docs",
-          content: "@docs",
-          start: 0,
-          end: 5,
-          mime: "application/x-directory",
-          filename: "docs",
-        },
-      ],
-      context: [],
-      images: [],
-      text: "@docs",
-      messageID: "msg_reference",
-      sessionID: "ses_reference",
-      sessionDirectory: "/repo/app",
-    })
-
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      expect(filePart.mime).toBe("application/x-directory")
-      expect(filePart.filename).toBe("docs")
-      expect(filePart.url).toBe("file:///repo/../docs")
-      expect(filePart.source?.type).toBe("file")
-      if (filePart.source?.type === "file") {
-        expect(filePart.source.path).toBe("/repo/../docs")
-        expect(filePart.source.text.value).toBe("@docs")
-      }
-    }
-  })
-
-  test("deduplicates context files when prompt already includes same path", () => {
-    const prompt: Prompt = [{ type: "file", path: "src/foo.ts", content: "@src/foo.ts", start: 0, end: 11 }]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [
-        { key: "ctx:dup", type: "file", path: "src/foo.ts" },
-        { key: "ctx:comment", type: "file", path: "src/foo.ts", comment: "focus here" },
-      ],
-      images: [],
-      text: "@src/foo.ts",
-      messageID: "msg_2",
-      sessionID: "ses_2",
-      sessionDirectory: "/repo",
-    })
-
-    const fooFiles = result.requestParts.filter(
-      (part) => part.type === "file" && part.url.startsWith("file:///repo/src/foo.ts"),
-    )
-    const synthetic = result.requestParts.filter((part) => part.type === "text" && part.synthetic)
-
-    expect(fooFiles).toHaveLength(2)
-    expect(synthetic).toHaveLength(1)
-  })
-
-  test("adds file parts for @mentions inside comment text", () => {
-    const result = buildRequestParts({
-      prompt: [{ type: "text", content: "look", start: 0, end: 4 }],
-      context: [
-        {
-          key: "ctx:comment-mention",
-          type: "file",
-          path: "src/review.ts",
-          comment: "Compare with @src/shared.ts and @src/review.ts.",
-        },
-      ],
-      images: [],
-      text: "look",
-      messageID: "msg_comment_mentions",
-      sessionID: "ses_comment_mentions",
-      sessionDirectory: "/repo",
-    })
-
-    const files = result.requestParts.filter((part) => part.type === "file")
-    expect(files).toHaveLength(2)
-    expect(files.some((part) => part.type === "file" && part.url === "file:///repo/src/review.ts")).toBe(true)
-    expect(files.some((part) => part.type === "file" && part.url === "file:///repo/src/shared.ts")).toBe(true)
-  })
-
-  test("handles Windows paths correctly (simulated on macOS)", () => {
-    const prompt: Prompt = [{ type: "file", path: "src\\foo.ts", content: "@src\\foo.ts", start: 0, end: 11 }]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [],
-      images: [],
-      text: "@src\\foo.ts",
-      messageID: "msg_win_1",
-      sessionID: "ses_win_1",
-      sessionDirectory: "D:\\projects\\myapp", // Windows path
-    })
-
-    // Should create valid file URLs
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      // URL should be parseable
-      expect(() => new URL(filePart.url)).not.toThrow()
-      // Should not have encoded backslashes in wrong place
-      expect(filePart.url).not.toContain("%5C")
-      // Should have normalized to forward slashes
-      expect(filePart.url).toContain("/src/foo.ts")
-    }
-  })
-
-  test("handles Windows absolute path with special characters", () => {
-    const prompt: Prompt = [{ type: "file", path: "file#name.txt", content: "@file#name.txt", start: 0, end: 14 }]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [],
-      images: [],
-      text: "@file#name.txt",
-      messageID: "msg_win_2",
-      sessionID: "ses_win_2",
-      sessionDirectory: "C:\\Users\\test\\Documents", // Windows path
-    })
-
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      // URL should be parseable
-      expect(() => new URL(filePart.url)).not.toThrow()
-      // Special chars should be encoded
-      expect(filePart.url).toContain("file%23name.txt")
-      // Should have Windows drive letter properly encoded
-      expect(filePart.url).toMatch(/file:\/\/\/[A-Z]:/)
-    }
-  })
-
-  test("handles Linux absolute paths correctly", () => {
-    const prompt: Prompt = [{ type: "file", path: "src/app.ts", content: "@src/app.ts", start: 0, end: 10 }]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [],
-      images: [],
-      text: "@src/app.ts",
-      messageID: "msg_linux_1",
-      sessionID: "ses_linux_1",
-      sessionDirectory: "/home/user/project",
-    })
-
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      // URL should be parseable
-      expect(() => new URL(filePart.url)).not.toThrow()
-      // Should be a normal Unix path
-      expect(filePart.url).toBe("file:///home/user/project/src/app.ts")
-    }
-  })
-
-  test("handles macOS paths correctly", () => {
-    const prompt: Prompt = [{ type: "file", path: "README.md", content: "@README.md", start: 0, end: 9 }]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [],
-      images: [],
-      text: "@README.md",
-      messageID: "msg_mac_1",
-      sessionID: "ses_mac_1",
-      sessionDirectory: "/Users/kelvin/Projects/opencode",
-    })
-
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      // URL should be parseable
-      expect(() => new URL(filePart.url)).not.toThrow()
-      // Should be a normal Unix path
-      expect(filePart.url).toBe("file:///Users/kelvin/Projects/opencode/README.md")
-    }
-  })
-
-  test("handles context files with Windows paths", () => {
-    const prompt: Prompt = []
-
-    const result = buildRequestParts({
-      prompt,
-      context: [
-        { key: "ctx:1", type: "file", path: "src\\utils\\helper.ts" },
-        { key: "ctx:2", type: "file", path: "test\\unit.test.ts", comment: "check tests" },
-      ],
-      images: [],
-      text: "test",
-      messageID: "msg_win_ctx",
-      sessionID: "ses_win_ctx",
-      sessionDirectory: "D:\\workspace\\app",
-    })
-
-    const fileParts = result.requestParts.filter((part) => part.type === "file")
-    expect(fileParts).toHaveLength(2)
-
-    // All file URLs should be valid
-    fileParts.forEach((part) => {
-      if (part.type === "file") {
-        expect(() => new URL(part.url)).not.toThrow()
-        expect(part.url).not.toContain("%5C") // No encoded backslashes
-      }
-    })
-  })
-
-  test("handles absolute Windows paths (user manually specifies full path)", () => {
-    const prompt: Prompt = [
-      { type: "file", path: "D:\\other\\project\\file.ts", content: "@D:\\other\\project\\file.ts", start: 0, end: 25 },
-    ]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [],
-      images: [],
-      text: "@D:\\other\\project\\file.ts",
-      messageID: "msg_abs",
-      sessionID: "ses_abs",
-      sessionDirectory: "C:\\current\\project",
-    })
-
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      // Should handle absolute path that differs from sessionDirectory
-      expect(() => new URL(filePart.url)).not.toThrow()
-      expect(filePart.url).toContain("/D:/other/project/file.ts")
-    }
-  })
-
-  test("handles selection with query parameters on Windows", () => {
-    const prompt: Prompt = [
-      {
-        type: "file",
-        path: "src\\App.tsx",
-        content: "@src\\App.tsx",
-        start: 0,
-        end: 11,
-        selection: { startLine: 10, startChar: 0, endLine: 20, endChar: 5 },
-      },
-    ]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [],
-      images: [],
-      text: "@src\\App.tsx",
-      messageID: "msg_sel",
-      sessionID: "ses_sel",
-      sessionDirectory: "C:\\project",
-    })
-
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      // Should have query parameters
-      expect(filePart.url).toContain("?start=10&end=20")
-      // Should be valid URL
-      expect(() => new URL(filePart.url)).not.toThrow()
-      // Query params should parse correctly
-      const url = new URL(filePart.url)
-      expect(url.searchParams.get("start")).toBe("10")
-      expect(url.searchParams.get("end")).toBe("20")
-    }
-  })
-
-  test("handles file paths with dots and special segments on Windows", () => {
-    const prompt: Prompt = [
-      { type: "file", path: "..\\..\\shared\\util.ts", content: "@..\\..\\shared\\util.ts", start: 0, end: 21 },
-    ]
-
-    const result = buildRequestParts({
-      prompt,
-      context: [],
-      images: [],
-      text: "@..\\..\\shared\\util.ts",
-      messageID: "msg_dots",
-      sessionID: "ses_dots",
-      sessionDirectory: "C:\\projects\\myapp\\src",
-    })
-
-    const filePart = result.requestParts.find((part) => part.type === "file")
-    expect(filePart).toBeDefined()
-    if (filePart?.type === "file") {
-      // Should be valid URL
-      expect(() => new URL(filePart.url)).not.toThrow()
-      // Should preserve .. segments (backend normalizes)
-      expect(filePart.url).toContain("/..")
-    }
-  })
-})
diff --git a/packages/app/src/components/prompt-input/build-request-parts.ts b/packages/app/src/components/prompt-input/build-request-parts.ts
deleted file mode 100644
index f23499a643a..00000000000
--- a/packages/app/src/components/prompt-input/build-request-parts.ts
+++ /dev/null
@@ -1,216 +0,0 @@
-import { getFilename } from "@opencode-ai/core/util/path"
-import type { AgentPart as MessageAgentPart, FilePart, Part, TextPart } from "@/types"
-import type { FileSelection } from "@/context/file"
-import { encodeFilePath } from "@/context/file/path"
-import type { AgentPart, FileAttachmentPart, ImageAttachmentPart, Prompt } from "@/context/prompt"
-import { Identifier } from "@/utils/id"
-import { createCommentMetadata, formatCommentNote } from "@/utils/comment-note"
-
-type PromptRequestPart =
-  | (Omit<TextPart, "id" | "sessionID" | "messageID"> & { id: string })
-  | (Omit<FilePart, "id" | "sessionID" | "messageID"> & { id: string })
-  | (Omit<MessageAgentPart, "id" | "sessionID" | "messageID"> & { id: string })
-
-type ContextFile = {
-  key: string
-  type: "file"
-  path: string
-  selection?: FileSelection
-  comment?: string
-  commentID?: string
-  commentOrigin?: "review" | "file"
-  preview?: string
-}
-
-type BuildRequestPartsInput = {
-  prompt: Prompt
-  context: ContextFile[]
-  images: (Omit<ImageAttachmentPart, "blob"> & { dataUrl: string })[]
-  text: string
-  messageID: string
-  sessionID: string
-  sessionDirectory: string
-}
-
-const absolute = (directory: string, path: string) => {
-  if (path.startsWith("/")) return path
-  if (/^[A-Za-z]:[\\/]/.test(path) || /^[A-Za-z]:$/.test(path)) return path
-  if (path.startsWith("\\\\") || path.startsWith("//")) return path
-  return `${directory.replace(/[\\/]+$/, "")}/${path}`
-}
-
-const fileQuery = (selection: FileSelection | undefined) =>
-  selection ? `?start=${selection.startLine}&end=${selection.endLine}` : ""
-
-const mention = /(^|[\s([{"'])@(\S+)/g
-
-const parseCommentMentions = (comment: string) => {
-  return Array.from(comment.matchAll(mention)).flatMap((match) => {
-    const path = (match[2] ?? "").replace(/[.,!?;:)}\]"']+$/, "")
-    if (!path) return []
-    return [path]
-  })
-}
-
-const isFileAttachment = (part: Prompt[number]): part is FileAttachmentPart => part.type === "file"
-const isAgentAttachment = (part: Prompt[number]): part is AgentPart => part.type === "agent"
-
-const toOptimisticPart = (part: PromptRequestPart, sessionID: string, messageID: string): Part => {
-  if (part.type === "text") {
-    return {
-      id: part.id,
-      type: "text",
-      text: part.text,
-      synthetic: part.synthetic,
-      ignored: part.ignored,
-      time: part.time,
-      metadata: part.metadata,
-      sessionID,
-      messageID,
-    }
-  }
-  if (part.type === "file") {
-    return {
-      id: part.id,
-      type: "file",
-      mime: part.mime,
-      filename: part.filename,
-      url: part.url,
-      source: part.source,
-      sessionID,
-      messageID,
-    }
-  }
-  return {
-    id: part.id,
-    type: "agent",
-    name: part.name,
-    source: part.source,
-    sessionID,
-    messageID,
-  }
-}
-
-export function buildRequestParts(input: BuildRequestPartsInput) {
-  const requestParts: PromptRequestPart[] = input.text.trim()
-    ? [
-        {
-          id: Identifier.ascending("part"),
-          type: "text",
-          text: input.text,
-        },
-      ]
-    : []
-
-  const files = input.prompt.filter(isFileAttachment).map((attachment) => {
-    const path = absolute(input.sessionDirectory, attachment.path)
-    const source = attachment.source
-      ? {
-          ...attachment.source,
-          text: {
-            value: attachment.content,
-            start: attachment.start,
-            end: attachment.end,
-          },
-        }
-      : {
-          type: "file" as const,
-          text: {
-            value: attachment.content,
-            start: attachment.start,
-            end: attachment.end,
-          },
-          path,
-        }
-    return {
-      id: Identifier.ascending("part"),
-      type: "file",
-      mime: attachment.mime ?? "text/plain",
-      url: attachment.url ?? `file://${encodeFilePath(path)}${fileQuery(attachment.selection)}`,
-      filename: attachment.filename ?? getFilename(attachment.path),
-      source,
-    } satisfies PromptRequestPart
-  })
-
-  const agents = input.prompt.filter(isAgentAttachment).map((attachment) => {
-    return {
-      id: Identifier.ascending("part"),
-      type: "agent",
-      name: attachment.name,
-      source: {
-        value: attachment.content,
-        start: attachment.start,
-        end: attachment.end,
-      },
-    } satisfies PromptRequestPart
-  })
-
-  const used = new Set(files.map((part) => part.url))
-  const context = input.context.flatMap((item) => {
-    const path = absolute(input.sessionDirectory, item.path)
-    const url = `file://${encodeFilePath(path)}${fileQuery(item.selection)}`
-    const comment = item.comment?.trim()
-    if (!comment && used.has(url)) return []
-    used.add(url)
-
-    const filePart = {
-      id: Identifier.ascending("part"),
-      type: "file",
-      mime: "text/plain",
-      url,
-      filename: getFilename(item.path),
-    } satisfies PromptRequestPart
-
-    if (!comment) return [filePart]
-
-    const mentions = parseCommentMentions(comment).flatMap((path) => {
-      const url = `file://${encodeFilePath(absolute(input.sessionDirectory, path))}`
-      if (used.has(url)) return []
-      used.add(url)
-      return [
-        {
-          id: Identifier.ascending("part"),
-          type: "file",
-          mime: "text/plain",
-          url,
-          filename: getFilename(path),
-        } satisfies PromptRequestPart,
-      ]
-    })
-
-    return [
-      {
-        id: Identifier.ascending("part"),
-        type: "text",
-        text: formatCommentNote({ path: item.path, selection: item.selection, comment }),
-        synthetic: true,
-        metadata: createCommentMetadata({
-          path: item.path,
-          selection: item.selection,
-          comment,
-          preview: item.preview,
-          origin: item.commentOrigin,
-        }),
-      } satisfies PromptRequestPart,
-      filePart,
-      ...mentions,
-    ]
-  })
-
-  const images = input.images.map((attachment) => {
-    return {
-      id: Identifier.ascending("part"),
-      type: "file",
-      mime: attachment.mime,
-      url: attachment.dataUrl,
-      filename: attachment.sourcePath ?? attachment.filename,
-    } satisfies PromptRequestPart
-  })
-
-  requestParts.push(...files, ...context, ...agents, ...images)
-
-  return {
-    requestParts,
-    optimisticParts: requestParts.map((part) => toOptimisticPart(part, input.sessionID, input.messageID)),
-  }
-}
diff --git a/packages/app/src/components/prompt-input/submit.test.ts b/packages/app/src/components/prompt-input/submit.test.ts
index ab905c28c67..c54bee7cfae 100644
--- a/packages/app/src/components/prompt-input/submit.test.ts
+++ b/packages/app/src/components/prompt-input/submit.test.ts
@@ -11,15 +11,17 @@ type SessionCreateInput = {
   model?: { id: string; providerID: string; variant?: string }
   location?: { directory: string }
 }
-const optimistic: Array<{
+const admitted: Array<{
   directory?: string
-  sessionID?: string
-  message: {
-    agent: string
-    model: { providerID: string; modelID: string }
-    variant?: string
-  }
+  sessionID: string
+  messageID: string
+  text: string
+  displayText: string
+  agent: string
+  model: { providerID: string; modelID: string; variant?: string }
+  comments: unknown[]
 }> = []
+const confirmed: unknown[] = []
 const storedSessions: Record<string, Array<{ id: string; title?: string }>> = {}
 const sentShell: Array<{ sessionID: string; id?: string; command: string }> = []
 const sentShellDirectories: string[] = []
@@ -35,9 +37,11 @@ const switchedModels: Array<{
 const sessionRequestOrder: string[] = []
 const updatedDrafts: Array<{ draftID: string; worktree?: string }> = []
 const syncedServers: string[] = []
-const optimisticServers: string[] = []
+const admittedServers: string[] = []
 const promptCaptures: Array<{ scope?: unknown; target?: unknown }> = []
 let serverSessionSyncs = 0
+let restoredPrompts = 0
+let clearEchoCalls = 0
 
 let params: { id?: string } = {}
 let search: { draftId?: string } = {}
@@ -47,6 +51,8 @@ let createSessionGate: Promise<void> | undefined
 let createWorktreeGate: Promise<void> | undefined
 let worktreeFailure: Error | undefined
 let locationFailure: Error | undefined
+let promptFailure: Error | undefined
+let clearEchoResult = true
 let worktreeCreates = 0
 let activeSDK = "server-a"
 let activeServerSync = "server-a"
@@ -74,7 +80,7 @@ const prompt = {
     set: () => undefined,
   },
   reset: () => undefined,
-  set: () => undefined,
+  set: () => restoredPrompts++,
   context: {
     add: () => undefined,
     remove: () => undefined,
@@ -116,7 +122,16 @@ const clientFor = (directory: string) => {
           sessionRequestOrder.push("prompt")
           sentPrompts.push(sessionDirectories[(input as { sessionID: string }).sessionID] ?? directory)
           promptInputs.push(input)
-          return { data: undefined }
+          if (promptFailure) throw promptFailure
+          const prompt = input as { sessionID: string; id: string; text: string }
+          return {
+            id: prompt.id,
+            sessionID: prompt.sessionID,
+            timeCreated: 1,
+            type: "user" as const,
+            delivery: "steer" as const,
+            payload: { text: prompt.text },
+          }
         },
         switchAgent: async (input: { sessionID: string; agent: string }) => {
           sessionRequestOrder.push("agent")
@@ -235,16 +250,27 @@ beforeAll(async () => {
       return {
         data: { command: commands, project: "project" },
         session: {
-          optimistic: {
-            add: (value: {
+          inbox: {
+            echo: (value: {
               directory?: string
-              sessionID?: string
-              message: { agent: string; model: { providerID: string; modelID: string; variant?: string } }
+              sessionID: string
+              messageID: string
+              text: string
+              displayText: string
+              agent: string
+              model: { providerID: string; modelID: string; variant?: string }
+              comments: unknown[]
             }) => {
-              optimisticServers.push(server)
-              optimistic.push(value)
+              admittedServers.push(server)
+              admitted.push(value)
+            },
+            confirm: (value: unknown) => {
+              confirmed.push(value)
+            },
+            clearEcho: () => {
+              clearEchoCalls++
+              return clearEchoResult
             },
-            remove: () => undefined,
           },
         },
         set: () => undefined,
@@ -304,7 +330,8 @@ beforeAll(async () => {
 
 beforeEach(() => {
   createdSessions.length = 0
-  optimistic.length = 0
+  admitted.length = 0
+  confirmed.length = 0
   promotedDrafts.length = 0
   updatedDrafts.length = 0
   sentCommands.length = 0
@@ -314,8 +341,10 @@ beforeEach(() => {
   switchedModels.length = 0
   sessionRequestOrder.length = 0
   syncedServers.length = 0
-  optimisticServers.length = 0
+  admittedServers.length = 0
   promptCaptures.length = 0
+  restoredPrompts = 0
+  clearEchoCalls = 0
   params = {}
   search = {}
   sentShell.length = 0
@@ -333,6 +362,8 @@ beforeEach(() => {
   createWorktreeGate = undefined
   worktreeFailure = undefined
   locationFailure = undefined
+  promptFailure = undefined
+  clearEchoResult = true
   worktreeCreates = 0
   for (const key of Object.keys(draftServers)) delete draftServers[key]
   for (const key of Object.keys(sessionDirectories)) delete sessionDirectories[key]
@@ -421,7 +452,7 @@ describe("prompt submit worktree selection", () => {
     expect(updatedDrafts).toEqual([{ draftID: "draft-1", worktree: undefined }])
     expect(promotedDrafts).toEqual([{ draftID: "draft-1", server: "project-server-a", sessionId: "session-1" }])
     expect(syncedServers.every((server) => server === "server-a")).toBe(true)
-    expect(optimisticServers).toEqual(["server-a"])
+    expect(admittedServers).toEqual(["server-a"])
     expect(promptCaptures.at(-1)?.target).toEqual({ server: "project-server-a", scope: ServerScope.local })
     expect(submitted).toBe(0)
   })
@@ -441,13 +472,15 @@ describe("prompt submit worktree selection", () => {
     await submit.handleSubmit(event)
     await Bun.sleep(0)
 
-    expect(optimistic).toHaveLength(1)
-    expect(optimistic[0]).toMatchObject({
-      message: {
-        agent: "agent",
-        model: { providerID: "provider", modelID: "model", variant: "high" },
-      },
+    expect(admitted).toHaveLength(1)
+    expect(admitted[0]).toMatchObject({
+      sessionID: "session-1",
+      text: "ls",
+      agent: "agent",
+      model: { providerID: "provider", modelID: "model", variant: "high" },
     })
+    expect(admitted[0]?.messageID).toStartWith("msg_")
+    expect(confirmed).toMatchObject([{ id: admitted[0]?.messageID, sessionID: "session-1" }])
     expect(sentPrompts).toEqual(["/repo/main"])
     expect(switchedAgents).toEqual([{ sessionID: "session-1", agent: "agent" }])
     expect(switchedModels).toEqual([
@@ -466,6 +499,22 @@ describe("prompt submit worktree selection", () => {
     expect((promptInputs[0] as { id?: string }).id).toStartWith("msg_")
   })
 
+  test("keeps a confirmed echo when the prompt response is lost", async () => {
+    params = { id: "session-1" }
+    promptFailure = new Error("connection lost")
+    clearEchoResult = false
+    const submit = makeSubmit({
+      info: () => ({ id: "session-1", agent: "agent", model: { id: "model", providerID: "provider" } }),
+    })
+
+    await submit.handleSubmit(event)
+    await settle()
+
+    expect(admitted).toHaveLength(1)
+    expect(clearEchoCalls).toBe(1)
+    expect(restoredPrompts).toBe(0)
+  })
+
   test("submits slash commands through the current session API", async () => {
     params = { id: "session-1" }
     variant = "high"
diff --git a/packages/app/src/components/prompt-input/submit.ts b/packages/app/src/components/prompt-input/submit.ts
index da717534f21..e2cdfc0fde3 100644
--- a/packages/app/src/components/prompt-input/submit.ts
+++ b/packages/app/src/components/prompt-input/submit.ts
@@ -1,10 +1,9 @@
-import type { Message } from "@/types"
 import type { SessionInfo } from "@opencode-ai/client/promise"
 import { showToast } from "@/utils/toast"
 import { base64Encode } from "@opencode-ai/core/util/encode"
 import { Binary } from "@opencode-ai/core/util/binary"
 import { useNavigate, useParams, useSearchParams } from "@solidjs/router"
-import { batch, startTransition, type Accessor } from "solid-js"
+import { startTransition, type Accessor } from "solid-js"
 import { useTabs } from "@/context/tabs"
 import { useServerSync, type ServerSync } from "@/context/server-sync"
 import { useLanguage } from "@/context/language"
@@ -15,7 +14,7 @@ import { useSDK, type DirectorySDK } from "@/context/sdk"
 import { useSync, type DirectorySync } from "@/context/sync"
 import { Identifier } from "@/utils/id"
 import { getDirectory } from "@opencode-ai/core/util/path"
-import { buildRequestParts } from "./build-request-parts"
+import { buildPromptRequest } from "./build-prompt-request"
 import { setCursorPosition } from "./editor-dom"
 import { formatServerError } from "@/utils/server-errors"
 import { ScopedKey } from "@/utils/server-scope"
@@ -100,43 +99,22 @@ export async function sendFollowupDraft(input: FollowupSendInput) {
       dataUrl: await blobDataUrl(attachment.blob, attachment.mime),
     })),
   )
-  const { requestParts, optimisticParts } = buildRequestParts({
+  const request = buildPromptRequest({
     prompt: input.draft.prompt,
     context: input.draft.context,
     images: encodedImages,
     text,
-    sessionID: input.draft.sessionID,
-    messageID,
     sessionDirectory: input.draft.sessionDirectory,
   })
 
-  const message: Message = {
-    id: messageID,
+  setBusy()
+  input.sync.session.inbox.echo({
+    directory: input.draft.sessionDirectory,
     sessionID: input.draft.sessionID,
-    role: "user",
-    time: { created: Date.now() },
+    messageID,
     agent: input.draft.agent,
     model: { ...input.draft.model, variant: input.draft.variant },
-  }
-
-  const add = () =>
-    input.sync.session.optimistic.add({
-      directory: input.draft.sessionDirectory,
-      sessionID: input.draft.sessionID,
-      message,
-      parts: optimisticParts,
-    })
-
-  const remove = () =>
-    input.sync.session.optimistic.remove({
-      directory: input.draft.sessionDirectory,
-      sessionID: input.draft.sessionID,
-      messageID,
-    })
-
-  batch(() => {
-    setBusy()
-    add()
+    ...request,
   })
 
   try {
@@ -159,40 +137,23 @@ export async function sendFollowupDraft(input: FollowupSendInput) {
       })
     }
 
-    await input.api.prompt({
+    const admitted = await input.api.prompt({
       sessionID: input.draft.sessionID,
       id: messageID,
-      text: requestParts.flatMap((part) => (part.type === "text" ? [part.text] : [])).join("\n"),
-      files: requestParts.flatMap((part) => {
-        if (part.type !== "file") return []
-        const text = part.source?.text
-        return [
-          {
-            uri: part.url,
-            name: part.filename,
-            mention: text ? { start: text.start, end: text.end, text: text.value } : undefined,
-          },
-        ]
-      }),
-      agents: requestParts.flatMap((part) =>
-        part.type === "agent"
-          ? [
-              {
-                name: part.name,
-                mention: part.source
-                  ? { start: part.source.start, end: part.source.end, text: part.source.value }
-                  : undefined,
-              },
-            ]
-          : [],
-      ),
+      text: request.text,
+      files: request.files.map((file) => ({ uri: file.uri, name: file.name, mention: file.mention })),
+      agents: request.agents,
     })
+    input.sync.session.inbox.confirm(admitted)
     return true
   } catch (err) {
-    batch(() => {
-      setIdle()
-      remove()
+    const failed = input.sync.session.inbox.clearEcho({
+      directory: input.draft.sessionDirectory,
+      sessionID: input.draft.sessionID,
+      messageID,
     })
+    if (!failed) return true
+    setIdle()
     throw err
   }
 }
@@ -538,14 +499,6 @@ export function createPromptSubmit(input: PromptSubmitInput) {
       const commentItems = context.filter((item) => item.type === "file" && !!item.comment?.trim())
       const messageID = Identifier.ascending("message")
 
-      const removeOptimisticMessage = () => {
-        submissionSync.session.optimistic.remove({
-          directory: sessionDirectory,
-          sessionID: session.id,
-          messageID,
-        })
-      }
-
       for (const item of commentItems) submission.target().context.remove(item.key)
       clearInput()
 
@@ -565,7 +518,6 @@ export function createPromptSubmit(input: PromptSubmitInput) {
           title: language.t("prompt.toast.promptSendFailed.title"),
           description: errorMessage(err),
         })
-        removeOptimisticMessage()
         if (restoreInput()) restoreCommentItems(submission.target(), commentItems)
       })
     } finally {
diff --git a/packages/app/src/context/directory-sync.ts b/packages/app/src/context/directory-sync.ts
index f1665e0b390..09e5ec7bba2 100644
--- a/packages/app/src/context/directory-sync.ts
+++ b/packages/app/src/context/directory-sync.ts
@@ -1,10 +1,10 @@
 import { Binary } from "@opencode-ai/core/util/binary"
-import type { Message, Part } from "@/types"
-import type { SessionInfo } from "@opencode-ai/client/promise"
+import type { SessionInboxInfo, SessionInfo } from "@opencode-ai/client/promise"
 import { createMemo } from "solid-js"
 import { produce, reconcile, type SetStoreFunction } from "solid-js/store"
 import type { createServerSdkContext } from "./server-sdk"
 import type { createServerSyncContextInner } from "./server-sync"
+import type { PromptEcho } from "./server-session"
 import type { State } from "./global-sync/types"
 
 const cmp = (a: string, b: string) => (a < b ? -1 : a > b ? 1 : 0)
@@ -82,34 +82,16 @@ export const createDirSyncContext = (
         const session = serverSync.session.get(sessionID)
         if (session?.location.directory === directory) return session
       },
-      optimistic: {
-        add(input: { directory?: string; sessionID: string; message: Message; parts: Part[] }) {
-          serverSync.session.optimistic.add(input)
+      inbox: {
+        echo(input: PromptEcho & { directory?: string }) {
+          serverSync.session.inbox.echo(input)
         },
-        remove(input: { directory?: string; sessionID: string; messageID: string }) {
-          serverSync.session.optimistic.remove(input)
+        confirm(input: SessionInboxInfo) {
+          return serverSync.session.inbox.confirm(input)
+        },
+        clearEcho(input: { directory?: string; sessionID: string; messageID: string }) {
+          return serverSync.session.inbox.clearEcho(input)
         },
-      },
-      addOptimisticMessage(input: {
-        sessionID: string
-        messageID: string
-        parts: Part[]
-        agent: string
-        model: { providerID: string; modelID: string }
-        variant?: string
-      }) {
-        serverSync.session.optimistic.add({
-          sessionID: input.sessionID,
-          message: {
-            id: input.messageID,
-            sessionID: input.sessionID,
-            role: "user",
-            time: { created: Date.now() },
-            agent: input.agent,
-            model: { ...input.model, variant: input.variant },
-          },
-          parts: input.parts,
-        })
       },
       async sync(sessionID: string, options?: { force?: boolean }) {
         await serverSync.session.sync(sessionID, options)
diff --git a/packages/app/src/context/file/path.test.ts b/packages/app/src/context/file/path.test.ts
index 99dd88ae0e9..e89bec7e7f2 100644
--- a/packages/app/src/context/file/path.test.ts
+++ b/packages/app/src/context/file/path.test.ts
@@ -143,7 +143,7 @@ describe("encodeFilePath", () => {
     })
 
     test("should handle mixed separator path (Windows + Unix)", () => {
-      // This is what happens in build-request-parts.ts when concatenating paths
+      // This is what happens in build-prompt-request.ts when concatenating paths
       const mixedPath = "D:\\dev\\projects\\opencode/README.bs.md"
       const result = encodeFilePath(mixedPath)
       const fileUrl = `file://${result}`
diff --git a/packages/app/src/context/server-session-v2-reducer.test.ts b/packages/app/src/context/server-session-v2-reducer.test.ts
index 0db44cb95d6..c18e2b668e3 100644
--- a/packages/app/src/context/server-session-v2-reducer.test.ts
+++ b/packages/app/src/context/server-session-v2-reducer.test.ts
@@ -6,6 +6,32 @@ const event = (input: object) => input as OpenCodeEvent
 const base = { created: 1, location: { directory: "/repo" }, durable: { aggregateID: "ses_1", seq: 1, version: 1 } }
 
 describe("v2 session reducer", () => {
+  test("moves a repeated inbox payload to the current event position", () => {
+    const reducer = createV2SessionReducer()
+    const result = reducer.reduce(
+      [
+        { id: "msg_user", type: "user", text: "local", time: { created: 0 } },
+        { id: "msg_agent", type: "agent-switched", agent: "review", time: { created: 1 } },
+      ],
+      event({
+        ...base,
+        id: "evt_admitted",
+        type: "session.inbox.enqueued",
+        data: {
+          sessionID: "ses_1",
+          inboxID: "msg_user",
+          item: { type: "user", delivery: "steer", payload: { text: "durable" } },
+        },
+      }),
+    )
+
+    expect(result?.messages).toEqual([
+      { id: "msg_agent", type: "agent-switched", agent: "review", time: { created: 1 } },
+      { id: "msg_user", type: "user", text: "durable", time: { created: 1 } },
+    ])
+    expect(result?.touched).toEqual(["msg_user"])
+  })
+
   test("projects promoted input and streaming assistant content", () => {
     const reducer = createV2SessionReducer()
     let messages: SessionMessageInfo[] = []
diff --git a/packages/app/src/context/server-session-v2-reducer.ts b/packages/app/src/context/server-session-v2-reducer.ts
index b03d1a1e0ee..c94443c8195 100644
--- a/packages/app/src/context/server-session-v2-reducer.ts
+++ b/packages/app/src/context/server-session-v2-reducer.ts
@@ -1,4 +1,10 @@
-import type { OpenCodeEvent, SessionInboxItem, SessionInfo, SessionMessageInfo } from "@opencode-ai/client/promise"
+import type {
+  OpenCodeEvent,
+  SessionInboxInfo,
+  SessionInboxItem,
+  SessionInfo,
+  SessionMessageInfo,
+} from "@opencode-ai/client/promise"
 
 type Assistant = Extract<SessionMessageInfo, { type: "assistant" }>
 type Compaction = Extract<SessionMessageInfo, { type: "compaction" }>
@@ -29,12 +35,14 @@ export function createV2SessionReducer() {
     })
     const append = (message: SessionMessageInfo) =>
       result(source.some((item) => item.id === message.id) ? [...source] : [...source, message], [message.id])
+    const replace = (message: SessionMessageInfo) =>
+      result([...source.filter((item) => item.id !== message.id), message], [message.id])
 
     switch (event.type) {
       case "session.inbox.enqueued":
         pending.set(key(sessionID, event.data.inboxID), event.data.item)
         if (event.data.item.type === "user")
-          return append({
+          return replace({
             id: event.data.inboxID,
             type: "user",
             metadata: event.data.item.payload.metadata,
@@ -44,7 +52,7 @@ export function createV2SessionReducer() {
             time: { created: event.created },
           })
         if (event.data.item.type !== "synthetic") return result([...source])
-        return append({
+        return replace({
           id: event.data.inboxID,
           type: "synthetic",
           metadata: event.data.item.payload.metadata,
@@ -480,6 +488,9 @@ export function createV2SessionReducer() {
 
   return {
     reduce,
+    confirm(item: SessionInboxInfo) {
+      pending.set(key(item.sessionID, item.id), item)
+    },
     clear(sessionID: string) {
       for (const id of pending.keys()) {
         if (id.startsWith(`${sessionID}:`)) pending.delete(id)
diff --git a/packages/app/src/context/server-session.test.ts b/packages/app/src/context/server-session.test.ts
index 22874d1b5d5..94bc0a9f3d8 100644
--- a/packages/app/src/context/server-session.test.ts
+++ b/packages/app/src/context/server-session.test.ts
@@ -185,6 +185,16 @@ const textPart = (messageID: string, input: Partial<TextPart> = {}): TextPart =>
   id: `${messageID}:text:${input.id === "pending" ? 1 : 0}`,
 })
 
+const promptEcho = (messageID: string, text = "hello") => ({
+  sessionID: "child",
+  messageID,
+  text,
+  displayText: text,
+  agent: "build",
+  model: { providerID: "provider", modelID: "model" },
+  comments: [],
+})
+
 const response = (data: MessageResponse["data"] = [], cursor?: string): MessageResponse => ({
   data,
   response: { headers: new Headers(cursor ? { "x-next-cursor": cursor } : undefined) },
@@ -299,6 +309,26 @@ function setup(sessions: Record<string, SessionInfo>) {
 }
 
 describe("server session", () => {
+  test("hydrates session info after a native session.created event", async () => {
+    const ctx = setup({ created: session("created") })
+
+    ctx.store.apply({
+      type: "session.created",
+      properties: {
+        sessionID: "created",
+        projectID: "project",
+        location: { directory: "/repo" },
+        slug: "created",
+        version: "test",
+      },
+    })
+
+    expect(ctx.store.get("created")).toBeUndefined()
+    await ctx.store.resolve("created")
+    expect(ctx.store.get("created")?.location.directory).toBe("/repo")
+    expect(ctx.get).toEqual([{ sessionID: "created" }])
+  })
+
   test("projects V2 session events into current and legacy message state", () => {
     const ctx = setup({ child: session("child") })
     ctx.store.remember(session("child"))
@@ -710,19 +740,17 @@ describe("server session", () => {
       expect(store.data.part[parent.id]).toBeUndefined()
     })
 
-    test("does not let an optimistic user suppress initial root backfill", async () => {
+    test("does not let an admitted user suppress initial root backfill", async () => {
       const user = userMessage("message-1")
-      const part = textPart(user.id)
       const assistants = [assistantMessage("message-2", user.id), assistantMessage("message-3", user.id)]
       const client = rootMessageClient(
         [response(assistants.map((info) => ({ info, parts: [] })))],
         [singleResponse(user)],
       )
       const store = createServerSession(client)
-      store.optimistic.add({ sessionID: "child", message: user, parts: [part] })
+      store.inbox.echo(promptEcho(user.id, "text"))
 
       await store.sync("child")
-      store.optimistic.remove({ sessionID: "child", messageID: user.id })
 
       expect(client.requests).toHaveLength(1)
       expect(client.rootRequests).toHaveLength(1)
@@ -783,28 +811,6 @@ describe("server session", () => {
       expect(store.data.part[stale.id]).toEqual([freshPart])
     })
 
-    test("refreshes a confirmed optimistic parent while preserving pending parts", async () => {
-      const stale = userMessage("message-1", { summary: { title: "stale", diffs: [] } })
-      const fresh = { ...stale, summary: { title: "fresh", diffs: [] } }
-      const confirmed = textPart(stale.id, { id: "confirmed", text: "stale" })
-      const refreshed = { ...confirmed, text: "fresh" }
-      const pending = textPart(stale.id, { id: "pending", text: "pending" })
-      const assistant = assistantMessage("message-2", stale.id)
-      const client = rootMessageClient(
-        [response([{ info: stale, parts: [confirmed] }]), response([{ info: assistant, parts: [] }])],
-        [singleResponse(fresh, [refreshed])],
-      )
-      const store = createServerSession(client)
-      store.optimistic.add({ sessionID: "child", message: stale, parts: [confirmed, pending] })
-      await store.sync("child")
-
-      await store.sync("child", { force: true })
-
-      expect(client.rootRequests).toEqual([{ sessionID: "child", messageID: stale.id }])
-      expect(store.data.message.child).toEqual([fresh, assistant])
-      expect(store.data.part[stale.id]).toEqual([refreshed, pending])
-    })
-
     test("uses a parent received by SSE during the replacement load", async () => {
       const pending = deferredResponse()
       const user = userMessage("message-1")
@@ -1040,30 +1046,6 @@ describe("server session", () => {
     expect(store.data.part[message.id]).toBeUndefined()
   })
 
-  test("preserves optimistic parts re-added after removal during a refresh", async () => {
-    const pending = deferredResponse()
-    const message = userMessage("message")
-    const stale = textPart(message.id, { id: "stale", text: "stale" })
-    const part = textPart(message.id, { id: "optimistic", text: "optimistic" })
-    const store = createServerSession(
-      messageClient(response([{ info: message, parts: [] }]), pending.promise, response()),
-    )
-    await store.sync("child")
-    const refreshing = store.sync("child", { force: true })
-
-    store.apply({ type: "message.removed", properties: { sessionID: "child", messageID: message.id } })
-    store.optimistic.add({ sessionID: "child", message, parts: [part] })
-    pending.resolve(response([{ info: message, parts: [stale] }]))
-    await refreshing
-
-    expect(store.data.message.child).toEqual([message])
-    expect(store.data.part[message.id]).toEqual([part])
-
-    await store.sync("child", { force: true })
-    expect(store.data.message.child).toEqual([message])
-    expect(store.data.part[message.id]).toEqual([part])
-  })
-
   test("drops stale event content omitted by a complete initial page", async () => {
     const stale = userMessage("stale")
     const store = createServerSession(messageClient(response()))
@@ -1085,170 +1067,309 @@ describe("server session", () => {
     expect(store.data.message.child).toEqual([live, fetched])
   })
 
-  test("does not restore removed optimistic content on refresh", async () => {
-    const message = userMessage("message")
-    const part = textPart(message.id, { text: "removed" })
-    const kept = { ...message, id: "kept" }
-    const keptPart = { ...part, id: "kept-part", messageID: kept.id }
-    const store = createServerSession(messageClient(response([{ info: kept, parts: [] }])))
-    store.optimistic.add({ sessionID: "child", message, parts: [part] })
-    store.optimistic.add({ sessionID: "child", message: kept, parts: [keptPart] })
-
-    store.apply({ type: "message.removed", properties: { sessionID: "child", messageID: message.id } })
-    store.apply({
-      type: "message.part.removed",
-      properties: { sessionID: "child", messageID: kept.id, partID: keptPart.id },
-    })
-    await store.sync("child", { force: true })
-
-    expect(store.data.message.child).toEqual([kept])
-    expect(store.data.part[message.id]).toBeUndefined()
-    expect(store.data.part[kept.id]).toBeUndefined()
-  })
-
-  test("replaces confirmed optimistic content with the initial page", async () => {
-    const optimistic = userMessage("message")
-    const fetched = { ...optimistic, time: { created: 2 } }
-    const store = createServerSession(messageClient(response([{ info: fetched, parts: [] }])))
-    store.optimistic.add({ sessionID: "child", message: optimistic, parts: [] })
-
-    await store.sync("child")
-
-    expect(store.data.message.child).toEqual([fetched])
-  })
-
-  test("replaces a confirmed optimistic part with fetched content", async () => {
-    const pending = deferredResponse()
-    const message = userMessage("message")
-    const optimistic = textPart(message.id, { text: "optimistic" })
-    const fetched = { ...optimistic, text: "fetched" }
-    const store = createServerSession(messageClient(pending.promise))
-    const loading = store.sync("child")
-
-    store.optimistic.add({ sessionID: "child", message, parts: [optimistic] })
-    pending.resolve(response([{ info: message, parts: [fetched] }]))
-    await loading
-
-    expect(store.data.part[message.id]).toEqual([fetched])
-  })
-
-  test("rolls back only unconfirmed optimistic parts", async () => {
-    const pending = deferredResponse()
-    const message = userMessage("message")
-    const confirmed = textPart(message.id, { id: "confirmed", text: "confirmed" })
-    const pendingPart = textPart(message.id, { id: "pending", text: "pending" })
-    const store = createServerSession(messageClient(pending.promise))
-    const loading = store.sync("child")
-    store.optimistic.add({ sessionID: "child", message, parts: [confirmed, pendingPart] })
-
-    pending.resolve(response([{ info: message, parts: [confirmed] }]))
-    await loading
-    store.optimistic.remove({ sessionID: "child", messageID: message.id })
-
-    expect(store.data.message.child).toEqual([message])
-    expect(store.data.part[message.id]).toEqual([confirmed])
-  })
-
-  test("updates confirmed optimistic parts from later pages", async () => {
-    const message = userMessage("message")
-    const confirmed = textPart(message.id, { id: "confirmed", text: "first" })
-    const updated = { ...confirmed, text: "updated" }
-    const pendingPart = textPart(message.id, { id: "pending", text: "pending" })
-    const store = createServerSession(
-      messageClient(response([{ info: message, parts: [confirmed] }]), response([{ info: message, parts: [updated] }])),
-    )
-    store.optimistic.add({ sessionID: "child", message, parts: [confirmed, pendingPart] })
-    await store.sync("child")
-
-    await store.sync("child", { force: true })
-    store.optimistic.remove({ sessionID: "child", messageID: message.id })
-
-    expect(store.data.part[message.id]).toEqual([updated])
-  })
-
-  test("does not restore a confirmed optimistic part after its removal event", async () => {
-    const message = userMessage("message")
-    const confirmed = textPart(message.id, { id: "confirmed", text: "confirmed" })
-    const pendingPart = textPart(message.id, { id: "pending", text: "pending" })
-    const store = createServerSession(
-      messageClient(response([{ info: message, parts: [confirmed] }]), response([{ info: message, parts: [] }])),
-    )
-    store.optimistic.add({ sessionID: "child", message, parts: [confirmed, pendingPart] })
-    await store.sync("child")
-    store.apply({
-      type: "message.part.removed",
-      properties: { sessionID: "child", messageID: message.id, partID: confirmed.id },
-    })
-
-    await store.sync("child", { force: true })
-
-    expect(store.data.part[message.id]).toEqual([pendingPart])
-  })
-
-  test("clears delta buffers when removing optimistic content", () => {
-    const message = userMessage("message")
-    const part = textPart(message.id, { text: "optimistic" })
+  test("echoes a prompt without changing durable message order", () => {
     const store = setup({ child: session("child") }).store
-    store.optimistic.add({ sessionID: "child", message, parts: [part] })
-    store.apply({
-      type: "message.part.delta",
-      properties: { sessionID: "child", messageID: message.id, partID: part.id, field: "text", delta: " delta" },
+
+    store.inbox.echo({
+      ...promptEcho("msg_prompt"),
+      text: "hello\nThe user made the following comment regarding line 4 of src/foo.ts: check this",
+      files: [{ uri: "file:///repo/src/foo.ts", mime: "text/plain", name: "foo.ts" }],
+      agents: [{ name: "explore" }],
+      comments: [
+        {
+          path: "src/foo.ts",
+          selection: { startLine: 4, startChar: 1, endLine: 4, endChar: 5 },
+          comment: "check this",
+          preview: "const value = 1",
+          origin: "review",
+        },
+      ],
     })
 
-    store.optimistic.remove({ sessionID: "child", messageID: message.id })
+    expect(store.data.pending.child).toMatchObject([{ id: "msg_prompt", type: "user", delivery: "steer" }])
+    expect(store.data.input.child).toEqual(["msg_prompt"])
+    expect(store.data.session_message.child).toBeUndefined()
+    expect(store.data.message.child?.map((message) => message.id)).toEqual(["msg_prompt"])
+    expect(store.data.part.msg_prompt).toMatchObject([
+      { id: "msg_prompt:agent:0", type: "agent", name: "explore" },
+      {
+        id: "msg_prompt:comment:0",
+        type: "text",
+        synthetic: true,
+        metadata: {
+          opencodeComment: {
+            path: "src/foo.ts",
+            selection: { startLine: 4, startChar: 1, endLine: 4, endChar: 5 },
+            comment: "check this",
+            preview: "const value = 1",
+            origin: "review",
+          },
+        },
+      },
+      { id: "msg_prompt:file:0", type: "file", filename: "foo.ts" },
+      { id: "msg_prompt:text:0", type: "text", text: "hello" },
+    ])
 
-    expect(store.data.part[message.id]).toBeUndefined()
-    expect(store.data.part_text_accum_delta[part.id]).toBeUndefined()
+    store.applyV2({
+      id: "evt_prompt",
+      created: 2,
+      type: "session.inbox.enqueued",
+      durable: { aggregateID: "child", seq: 1, version: 1 },
+      data: {
+        sessionID: "child",
+        inboxID: "msg_prompt",
+        item: {
+          type: "user",
+          delivery: "steer",
+          payload: {
+            text: "hello\nThe user made the following comment regarding line 4 of src/foo.ts: check this",
+          },
+        },
+      },
+    } as OpenCodeEvent)
+
+    expect(store.data.part.msg_prompt).toMatchObject([
+      { id: "msg_prompt:comment:0", type: "text", synthetic: true },
+      { id: "msg_prompt:text:0", type: "text", text: "hello" },
+    ])
   })
 
-  test("removes projected messages when rolling back optimistic content", () => {
-    const message = userMessage("message")
-    const store = setup({ child: session("child") }).store
-    store.optimistic.add({ sessionID: "child", message, parts: [] })
+  test("preserves a local echo while message history omits pending input", async () => {
+    const store = createServerSession(messageClient(response()))
+    store.inbox.echo(promptEcho("msg_prompt"))
+    store.inbox.confirm({
+      id: "msg_prompt",
+      sessionID: "child",
+      timeCreated: 1,
+      type: "user",
+      delivery: "steer",
+      payload: { text: "hello" },
+    })
 
-    store.optimistic.remove({ sessionID: "child", messageID: message.id })
+    await store.sync("child")
 
+    expect(store.data.message.child?.map((message) => message.id)).toEqual(["msg_prompt"])
+    expect(store.data.part.msg_prompt).toMatchObject([{ type: "text", text: "hello" }])
+  })
+
+  test("preserves local comment presentation through message refresh", async () => {
+    const note = "The user made the following comment regarding line 4 of src/foo.ts: check this"
+    const message = userMessage("msg_prompt")
+    const store = createServerSession(
+      messageClient(response([{ info: message, parts: [textPart(message.id, { text: note })] }])),
+    )
+    store.inbox.echo({
+      ...promptEcho(message.id),
+      text: `hello\n${note}`,
+      comments: [
+        {
+          path: "src/foo.ts",
+          selection: { startLine: 4, startChar: 1, endLine: 4, endChar: 5 },
+          comment: "check this",
+          origin: "review",
+        },
+      ],
+    })
+
+    await store.sync("child")
+
+    expect(store.data.part.msg_prompt).toMatchObject([
+      { id: "msg_prompt:comment:0", type: "text", synthetic: true },
+      { id: "msg_prompt:text:0", type: "text", text: "hello" },
+    ])
+  })
+
+  test("retires an admitted echo absent from authoritative reconnect state", async () => {
+    const store = createServerSession(messageClient(response()))
+    store.inbox.echo(promptEcho("msg_prompt"))
+    store.inbox.confirm({
+      id: "msg_prompt",
+      sessionID: "child",
+      timeCreated: 1,
+      type: "user",
+      delivery: "steer",
+      payload: { text: "hello" },
+    })
+
+    await Promise.all([store.sync("child"), store.hydrateTransient("child", async () => ({ pending: [], forms: [] }))])
+    store.inbox.reconcile("child")
+
+    expect(store.data.pending.child).toEqual([])
+    expect(store.data.message.child).toEqual([])
+    expect(store.data.part.msg_prompt).toBeUndefined()
+  })
+
+  test("retires a stale enqueued message when inbox hydration finishes after history", async () => {
+    const store = createServerSession(messageClient(response()))
+    store.applyV2({
+      id: "evt_prompt",
+      created: 1,
+      type: "session.inbox.enqueued",
+      durable: { aggregateID: "child", seq: 1, version: 1 },
+      data: {
+        sessionID: "child",
+        inboxID: "msg_prompt",
+        item: { type: "user", delivery: "steer", payload: { text: "hello" } },
+      },
+    } as OpenCodeEvent)
+
+    await store.sync("child")
+    await store.hydrateTransient("child", async () => ({ pending: [], forms: [] }))
+    store.inbox.reconcile("child")
+
+    expect(store.data.pending.child).toEqual([])
     expect(store.data.session_message.child).toEqual([])
+    expect(store.data.message.child).toEqual([])
+    expect(store.data.part.msg_prompt).toBeUndefined()
   })
 
-  test("does not remove content confirmed by a message event", () => {
-    const message = userMessage("message")
-    const part = textPart(message.id)
+  test("deduplicates the durable admission event against its local echo", () => {
     const store = setup({ child: session("child") }).store
-    store.optimistic.add({ sessionID: "child", message, parts: [part] })
-    store.apply({ type: "message.updated", properties: { sessionID: "child", info: message } })
+    store.inbox.echo(promptEcho("msg_prompt"))
 
-    store.optimistic.remove({ sessionID: "child", messageID: message.id })
+    store.applyV2({
+      id: "evt_prompt",
+      created: 2,
+      type: "session.inbox.enqueued",
+      durable: { aggregateID: "child", seq: 1, version: 1 },
+      data: {
+        sessionID: "child",
+        inboxID: "msg_prompt",
+        item: { type: "user", delivery: "steer", payload: { text: "hello" } },
+      },
+    } as OpenCodeEvent)
 
-    expect(store.data.message.child).toEqual([message])
-    expect(store.data.part[message.id]).toBeUndefined()
+    expect(store.data.pending.child).toHaveLength(1)
+    expect(store.data.input.child).toEqual(["msg_prompt"])
+    expect(store.data.session_message.child?.filter((message) => message.id === "msg_prompt")).toHaveLength(1)
+    expect(store.data.message.child?.filter((message) => message.id === "msg_prompt")).toHaveLength(1)
+    expect(store.data.part.msg_prompt).toMatchObject([{ type: "text", text: "hello" }])
   })
 
-  test("does not remove parts confirmed by part events", () => {
-    const message = userMessage("message")
-    const part = textPart(message.id)
+  test("uses the prompt response when the admission event was missed", () => {
     const store = setup({ child: session("child") }).store
-    store.optimistic.add({ sessionID: "child", message, parts: [part] })
-    store.apply({ type: "message.updated", properties: { sessionID: "child", info: message } })
-    store.apply({ type: "message.part.updated", properties: { sessionID: "child", part, time: 2 } })
+    store.inbox.echo(promptEcho("msg_prompt"))
+    store.inbox.confirm({
+      id: "msg_prompt",
+      sessionID: "child",
+      timeCreated: 2,
+      type: "user",
+      delivery: "steer",
+      payload: { text: "hello" },
+    })
 
-    store.optimistic.remove({ sessionID: "child", messageID: message.id })
+    store.applyV2({
+      id: "evt_delivered",
+      created: Date.now() + 1,
+      type: "session.inbox.delivered",
+      durable: { aggregateID: "child", seq: 2, version: 1 },
+      data: { sessionID: "child", inboxID: "msg_prompt" },
+    } as OpenCodeEvent)
 
-    expect(store.data.message.child).toEqual([message])
-    expect(store.data.part[message.id]).toEqual([part])
+    expect(store.data.pending.child).toEqual([])
+    expect(store.data.input.child).toEqual([])
+    expect(store.data.session_message.child).toMatchObject([{ id: "msg_prompt", type: "user", text: "hello" }])
+    expect(store.data.message.child?.filter((message) => message.id === "msg_prompt")).toHaveLength(1)
+    expect(store.data.part.msg_prompt).toMatchObject([{ type: "text", text: "hello" }])
   })
 
-  test("treats a part event as confirmation when it precedes the message event", () => {
-    const message = userMessage("message")
-    const part = textPart(message.id)
+  test("keeps a durable admission when the HTTP request later fails", () => {
     const store = setup({ child: session("child") }).store
-    store.optimistic.add({ sessionID: "child", message, parts: [part] })
-    store.apply({ type: "message.part.updated", properties: { sessionID: "child", part, time: 2 } })
+    store.inbox.echo(promptEcho("msg_prompt"))
+    store.applyV2({
+      id: "evt_prompt",
+      created: 2,
+      type: "session.inbox.enqueued",
+      durable: { aggregateID: "child", seq: 1, version: 1 },
+      data: {
+        sessionID: "child",
+        inboxID: "msg_prompt",
+        item: { type: "user", delivery: "steer", payload: { text: "hello" } },
+      },
+    } as OpenCodeEvent)
 
-    store.optimistic.remove({ sessionID: "child", messageID: message.id })
+    expect(store.inbox.clearEcho({ sessionID: "child", messageID: "msg_prompt" })).toBe(false)
+    expect(store.data.pending.child).toHaveLength(1)
+    expect(store.data.message.child?.map((message) => message.id)).toEqual(["msg_prompt"])
+  })
 
-    expect(store.data.message.child).toEqual([message])
-    expect(store.data.part[message.id]).toEqual([part])
+  test("places durable admission after delayed selection events", () => {
+    const store = setup({ child: session("child") }).store
+    store.remember(session("child"))
+    store.inbox.echo(promptEcho("msg_prompt"))
+    store.applyV2({
+      id: "evt_agent",
+      created: 1,
+      type: "session.agent.selected",
+      durable: { aggregateID: "child", seq: 1, version: 1 },
+      data: { sessionID: "child", agent: "review" },
+    } as OpenCodeEvent)
+    store.applyV2({
+      id: "evt_model",
+      created: 2,
+      type: "session.model.selected",
+      durable: { aggregateID: "child", seq: 2, version: 1 },
+      data: { sessionID: "child", model: { id: "new-model", providerID: "new-provider" } },
+    } as OpenCodeEvent)
+    store.applyV2({
+      id: "evt_prompt",
+      created: 3,
+      type: "session.inbox.enqueued",
+      durable: { aggregateID: "child", seq: 3, version: 1 },
+      data: {
+        sessionID: "child",
+        inboxID: "msg_prompt",
+        item: { type: "user", delivery: "steer", payload: { text: "hello" } },
+      },
+    } as OpenCodeEvent)
+
+    expect(store.data.session_message.child?.map((message) => message.type)).toEqual([
+      "agent-switched",
+      "model-switched",
+      "user",
+    ])
+    expect(store.data.message.child?.find((message) => message.id === "msg_prompt")).toMatchObject({
+      agent: "review",
+      model: { providerID: "new-provider", modelID: "new-model" },
+    })
+  })
+
+  test("removes an echoed prompt when submission fails", () => {
+    const store = setup({ child: session("child") }).store
+    store.inbox.echo(promptEcho("msg_prompt"))
+
+    expect(store.inbox.clearEcho({ sessionID: "child", messageID: "msg_prompt" })).toBe(true)
+
+    expect(store.data.pending.child).toEqual([])
+    expect(store.data.input.child).toEqual([])
+    expect(store.data.session_message.child).toBeUndefined()
+    expect(store.data.message.child).toEqual([])
+    expect(store.data.part.msg_prompt).toBeUndefined()
+  })
+
+  test("removes a response-confirmed echo when the server cancels it", () => {
+    const store = setup({ child: session("child") }).store
+    store.inbox.echo(promptEcho("msg_prompt"))
+    store.inbox.confirm({
+      id: "msg_prompt",
+      sessionID: "child",
+      timeCreated: 1,
+      type: "user",
+      delivery: "steer",
+      payload: { text: "hello" },
+    })
+
+    store.applyV2({
+      id: "evt_cancelled",
+      created: 2,
+      type: "session.inbox.cancelled",
+      durable: { aggregateID: "child", seq: 2, version: 1 },
+      data: { sessionID: "child", inboxID: "msg_prompt" },
+    } as OpenCodeEvent)
+
+    expect(store.data.pending.child).toEqual([])
+    expect(store.data.message.child).toEqual([])
+    expect(store.data.part.msg_prompt).toBeUndefined()
   })
 
   test("clears stale parts when the initial page has none", async () => {
@@ -1469,28 +1590,6 @@ describe("server session", () => {
     expect(store.data.part[message.id]).toBeUndefined()
   })
 
-  test("preserves optimistic re-adds across message retries", async () => {
-    const failed = Promise.withResolvers<MessageResponse>()
-    const retried = Promise.withResolvers<MessageResponse>()
-    const message = userMessage("message")
-    const stale = textPart(message.id, { id: "stale", text: "stale" })
-    const optimistic = textPart(message.id, { id: "optimistic", text: "optimistic" })
-    const client = messageClient(response([{ info: message, parts: [stale] }]), failed.promise, retried.promise)
-    const store = createServerSession(client, { retry: retryImmediately })
-    await store.sync("child")
-    const loading = store.sync("child", { force: true })
-
-    store.apply({ type: "message.removed", properties: { sessionID: "child", messageID: message.id } })
-    store.optimistic.add({ sessionID: "child", message, parts: [optimistic] })
-    failed.reject(new Error("failed to fetch"))
-    await client.requested(3)
-    retried.resolve(response([{ info: message, parts: [stale] }]))
-    await loading
-
-    expect(store.data.message.child).toEqual([message])
-    expect(store.data.part[message.id]).toEqual([optimistic])
-  })
-
   test("accepts part omission from a successful retry after an earlier delta", async () => {
     const failed = Promise.withResolvers<MessageResponse>()
     const retried = Promise.withResolvers<MessageResponse>()
@@ -1654,33 +1753,6 @@ describe("server session", () => {
     expect(store.data.part[message.id]).toBeUndefined()
   })
 
-  test("does not cache skipped optimistic parts", () => {
-    const message = userMessage("message")
-    const part = { id: "part", sessionID: "child", messageID: message.id, type: "step-start" as const }
-    const store = setup({ child: session("child") }).store
-
-    store.optimistic.add({ sessionID: "child", message, parts: [part] })
-
-    expect(store.data.part[message.id]).toEqual([])
-  })
-
-  test("clears stale delta buffers when replacing optimistic parts", () => {
-    const message = userMessage("message")
-    const stale = textPart(message.id, { id: "stale", text: "stale" })
-    const optimistic = textPart(message.id, { id: "optimistic", text: "optimistic" })
-    const store = setup({ child: session("child") }).store
-    store.optimistic.add({ sessionID: "child", message, parts: [stale] })
-    store.apply({
-      type: "message.part.delta",
-      properties: { sessionID: "child", messageID: message.id, partID: stale.id, field: "text", delta: " delta" },
-    })
-
-    store.optimistic.add({ sessionID: "child", message, parts: [optimistic] })
-
-    expect(store.data.part_text_accum_delta[stale.id]).toBeUndefined()
-    expect(store.data.part_text_accum_delta[optimistic.id]).toBeUndefined()
-  })
-
   test("preserves removals during history prepend", async () => {
     const pending = deferredResponse()
     const latest = userMessage("message-2", { time: { created: 2 } })
@@ -1906,24 +1978,7 @@ describe("server session", () => {
   test("preserves pinned session content under server-wide cache pressure", () => {
     const ctx = setup({})
     ctx.store.pin("active")
-    ctx.store.optimistic.add({
-      sessionID: "active",
-      message: {
-        id: "message",
-        sessionID: "active",
-        role: "assistant",
-        time: { created: 1 },
-        parentID: "parent",
-        modelID: "model",
-        providerID: "provider",
-        mode: "build",
-        agent: "agent",
-        path: { cwd: "/repo", root: "/repo" },
-        cost: 0,
-        tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
-      },
-      parts: [],
-    })
+    ctx.store.inbox.echo({ ...promptEcho("message", "keep"), sessionID: "active" })
 
     for (let index = 0; index < 50; index++) {
       ctx.store.remember(session(`session-${index}`))
diff --git a/packages/app/src/context/server-session.ts b/packages/app/src/context/server-session.ts
index 193dde10e04..19cc5830b07 100644
--- a/packages/app/src/context/server-session.ts
+++ b/packages/app/src/context/server-session.ts
@@ -18,6 +18,13 @@ import { compareMessages, messageKey, normalizeSessionMessages } from "@/utils/s
 import { dropSessionCaches, pickSessionCacheEvictions, SESSION_CACHE_LIMIT } from "./global-sync/session-cache"
 import { createV2SessionReducer, type V2SessionReduction } from "./server-session-v2-reducer"
 import type { ServerApi } from "@/utils/server"
+import {
+  createCommentMetadata,
+  formatCommentNote,
+  parseCommentNote,
+  readCommentMetadata,
+  type PromptComment,
+} from "@/utils/comment-note"
 
 type MessageApi = ServerApi["message"]
 
@@ -28,31 +35,6 @@ const historyMessagePageSize = 200
 const sessionInfoLimit = 2_048
 const emptyIDs: ReadonlySet<string> = new Set()
 
-function projectMessageSource(message: Message): SessionMessageInfo[] {
-  if (message.role === "user") {
-    return [
-      { id: `${message.id}:agent`, type: "agent-switched", agent: message.agent, time: message.time },
-      {
-        id: `${message.id}:model`,
-        type: "model-switched",
-        model: { id: message.model.modelID, providerID: message.model.providerID, variant: message.model.variant },
-        time: message.time,
-      },
-      { id: message.id, type: "user", text: "", time: message.time },
-    ]
-  }
-  return [
-    {
-      id: message.id,
-      type: "assistant",
-      agent: message.agent ?? message.mode,
-      model: { id: message.modelID, providerID: message.providerID, variant: message.variant },
-      content: [],
-      time: message.time,
-    },
-  ]
-}
-
 function needsOlderTurnRoot(source: readonly SessionMessageInfo[]) {
   const boundary = source.find(
     (message) =>
@@ -64,13 +46,6 @@ function needsOlderTurnRoot(source: readonly SessionMessageInfo[]) {
   return boundary?.type === "assistant"
 }
 
-type OptimisticItem = {
-  message: Message
-  parts: Part[]
-  confirmedParts?: Part[]
-  confirmedMessage?: boolean
-}
-
 type MessagePage = {
   session: Message[]
   part: { id: string; part: Part[] }[]
@@ -81,6 +56,18 @@ type MessagePage = {
   complete: boolean
 }
 
+export type PromptEcho = {
+  sessionID: string
+  messageID: string
+  text: string
+  displayText: string
+  agent: string
+  model: { providerID: string; modelID: string; variant?: string }
+  files?: { uri: string; mime: string; name?: string; mention?: { start: number; end: number; text: string } }[]
+  agents?: { name: string; mention?: { start: number; end: number; text: string } }[]
+  comments: PromptComment[]
+}
+
 // Most markers describe the current HTTP attempt; deltaParts persists non-durable stream state across retries.
 type MessageLoadState = {
   touchedMessages: Set<string>
@@ -90,7 +77,6 @@ type MessageLoadState = {
   deltaParts: Map<string, Set<string>>
   carriedDeltaParts: Map<string, Set<string>>
   removedParts: Map<string, Set<string>>
-  optimisticParts: Map<string, Set<string>>
   orphanParents: Set<string>
   clearedMessageParts: Set<string>
   touchedSource: Set<string>
@@ -101,34 +87,6 @@ type MessageLoadBaseline = Pick<
   "touchedMessages" | "retainedMessages" | "touchedParts" | "clearedMessageParts"
 >
 
-function mergeOptimisticPage(page: MessagePage, items: OptimisticItem[]) {
-  if (items.length === 0) return { ...page, observed: [] as { messageID: string; parts: Part[] }[] }
-  const session = [...page.session]
-  const part = new Map(page.part.map((item) => [item.id, item.part]))
-  const observed: { messageID: string; parts: Part[] }[] = []
-  for (const item of items) {
-    const result = Binary.search(session, messageKey(item.message), messageKey)
-    const found = result.found
-    if (!found) session.splice(result.index, 0, item.message)
-    const current = part.get(item.message.id)
-    const confirmed = found ? item.parts.filter((part) => current?.some((value) => value.id === part.id)) : []
-    if (found) observed.push({ messageID: item.message.id, parts: confirmed })
-    part.set(
-      item.message.id,
-      merge(
-        found ? (current ?? []) : merge(item.confirmedParts ?? [], current ?? []),
-        item.parts.filter((part) => !confirmed.includes(part)),
-      ),
-    )
-  }
-  return {
-    ...page,
-    session,
-    part: [...part.entries()].sort((a, b) => cmp(a[0], b[0])).map(([id, parts]) => ({ id, part: parts })),
-    observed,
-  }
-}
-
 function runInflight(map: Map<string, Promise<void>>, key: string, task: () => Promise<void>) {
   const pending = map.get(key)
   if (pending) return pending
@@ -212,7 +170,6 @@ export function createServerSession(
   const requests = new Map<string, Promise<SessionInfo>>()
   const inflight = new Map<string, Promise<void>>()
   const inflightTodo = new Map<string, Promise<void>>()
-  const optimistic = new Map<string, Map<string, OptimisticItem>>()
   const v2 = createV2SessionReducer()
   const pendingRevision = new Map<string, number>()
   const formRevision = new Map<string, number>()
@@ -223,7 +180,45 @@ export function createServerSession(
   const pendingParts = new Map<string, Map<string, Set<string>>>()
   const orphanParts = new Map<string, Set<string>>()
   const removedMessages = new Map<string, Set<string>>()
+  const echoes = new Map<string, Map<string, "sending" | "admitted">>()
+  const messageSnapshots = new Map<string, Set<string>>()
+  const settledInputs = new Map<string, Set<string>>()
   const deltaBases = new Map<string, { base: string; sessionID: string }>()
+  const markEcho = (sessionID: string, messageID: string) => {
+    const messages = echoes.get(sessionID) ?? new Map<string, "sending" | "admitted">()
+    messages.set(messageID, "sending")
+    echoes.set(sessionID, messages)
+  }
+  const confirmEcho = (sessionID: string, messageID: string) => {
+    const messages = echoes.get(sessionID)
+    if (!messages?.has(messageID)) return false
+    messages.set(messageID, "admitted")
+    return true
+  }
+  const releaseEcho = (sessionID: string, messageID: string) => {
+    const messages = echoes.get(sessionID)
+    const state = messages?.get(messageID)
+    if (!messages || !state) return
+    messages.delete(messageID)
+    if (messages.size === 0) echoes.delete(sessionID)
+    return state
+  }
+  const present = (messageID: string, parts: Part[]) => {
+    const local = data.part[messageID] ?? []
+    const comments = local.filter(
+      (part) =>
+        part.type === "text" &&
+        part.synthetic &&
+        (readCommentMetadata(part.metadata) !== undefined || parseCommentNote(part.text) !== undefined),
+    )
+    if (!comments.length) return parts
+    const text = local.find((part) => part.type === "text" && !part.synthetic)
+    const projected = parts.flatMap((part) => {
+      if (part.id !== `${messageID}:text:0` || part.type !== "text") return [part]
+      return text?.type === "text" && text.text ? [{ ...part, text: text.text }] : []
+    })
+    return merge(projected, comments)
+  }
   const deleteMessageParts = (
     cache: { part: Record<string, Part[] | undefined>; part_text_accum_delta: Record<string, string | undefined> },
     messageID: string,
@@ -253,18 +248,6 @@ export function createServerSession(
     at: {} as Record<string, number | undefined>,
   })
 
-  const indexProjectedMessage = (message: Message) => {
-    const current = data.session_message[message.sessionID] ?? []
-    if (current.some((item) => item.id === message.id)) return
-    const projected = projectMessageSource(message)
-    const projectedIDs = new Set(projected.map((item) => item.id))
-    setData(
-      "session_message",
-      message.sessionID,
-      reconcile([...current.filter((item) => !projectedIDs.has(item.id)), ...projected]),
-    )
-  }
-
   const remember = (session: SessionInfo) => {
     setData("info", session.id, reconcile(session))
     infoSeen.delete(session.id)
@@ -276,7 +259,7 @@ export function createServerSession(
         ...inflight.keys(),
         ...inflightTodo.keys(),
         ...messageLoads.keys(),
-        ...optimistic.keys(),
+        ...echoes.keys(),
         ...Object.entries(data.permission)
           .filter(([, items]) => items.length > 0)
           .map(([sessionID]) => sessionID),
@@ -352,65 +335,6 @@ export function createServerSession(
     return { session, root }
   }
 
-  const clearOptimistic = (sessionID: string, messageID?: string) => {
-    if (!messageID) {
-      optimistic.delete(sessionID)
-      return
-    }
-    const items = optimistic.get(sessionID)
-    if (!items) return
-    items.delete(messageID)
-    if (items.size === 0) optimistic.delete(sessionID)
-  }
-
-  const clearOptimisticPart = (sessionID: string, messageID: string, partID: string) => {
-    const items = optimistic.get(sessionID)
-    const item = items?.get(messageID)
-    if (!items || !item) return
-    const parts = item.parts.filter((part) => part.id !== partID)
-    const confirmedParts = item.confirmedParts?.filter((part) => part.id !== partID)
-    if (parts.length === 0) {
-      clearOptimistic(sessionID, messageID)
-      return
-    }
-    items.set(messageID, { ...item, parts, confirmedParts, confirmedMessage: true })
-  }
-
-  const confirmOptimisticPart = (sessionID: string, messageID: string, part: Part) => {
-    const items = optimistic.get(sessionID)
-    const item = items?.get(messageID)
-    if (!items || !item) return
-    const parts = item.parts.filter((value) => value.id !== part.id)
-    if (parts.length === 0) {
-      clearOptimistic(sessionID, messageID)
-      return
-    }
-    items.set(messageID, {
-      ...item,
-      parts,
-      confirmedParts: merge(item.confirmedParts ?? [], [part]),
-      confirmedMessage: true,
-    })
-  }
-
-  const confirmOptimistic = (sessionID: string, messageID: string, confirmedParts: Part[]) => {
-    const items = optimistic.get(sessionID)
-    const item = items?.get(messageID)
-    if (!items || !item) return
-    const confirmed = new Set(confirmedParts.map((part) => part.id))
-    const parts = item.parts.filter((part) => !confirmed.has(part.id))
-    if (parts.length === 0) {
-      clearOptimistic(sessionID, messageID)
-      return
-    }
-    items.set(messageID, {
-      ...item,
-      parts,
-      confirmedParts: merge(item.confirmedParts ?? [], confirmedParts),
-      confirmedMessage: true,
-    })
-  }
-
   const trackPartChange = (sessionID: string, messageID: string, partID: string) => {
     const load = messageLoads.get(sessionID)
     if (!load) return
@@ -448,14 +372,6 @@ export function createServerSession(
       const messages = data.message[sessionID]
       if (messages?.some((message) => message.id === messageID)) load.retainedMessages.add(messageID)
     }
-    for (const [messageID, parts] of load.optimisticParts) {
-      load.removedMessages.delete(messageID)
-      load.clearedMessageParts.add(messageID)
-      load.touchedMessages.add(messageID)
-      const touched = load.touchedParts.get(messageID) ?? new Set<string>()
-      parts.forEach((partID) => touched.add(partID))
-      load.touchedParts.set(messageID, touched)
-    }
     baseline?.touchedMessages.forEach((messageID) => load.touchedMessages.add(messageID))
     baseline?.retainedMessages.forEach((messageID) => load.retainedMessages.add(messageID))
     baseline?.clearedMessageParts.forEach((messageID) => load.clearedMessageParts.add(messageID))
@@ -486,7 +402,9 @@ export function createServerSession(
     sessionIDs.forEach((sessionID) => {
       messageHydrationRevision.set(sessionID, (messageHydrationRevision.get(sessionID) ?? 0) + 1)
       generations.delete(sessionID)
-      clearOptimistic(sessionID)
+      echoes.delete(sessionID)
+      messageSnapshots.delete(sessionID)
+      settledInputs.delete(sessionID)
       requests.delete(sessionID)
       inflight.delete(sessionID)
       inflightTodo.delete(sessionID)
@@ -521,7 +439,7 @@ export function createServerSession(
       ...inflight.keys(),
       ...inflightTodo.keys(),
       ...messageLoads.keys(),
-      ...optimistic.keys(),
+      ...echoes.keys(),
       ...Object.entries(data.permission)
         .filter(([, items]) => items.length > 0)
         .map(([sessionID]) => sessionID),
@@ -598,9 +516,10 @@ export function createServerSession(
   ) => {
     for (const item of items) {
       if (!messageIDs.has(item.id)) continue
-      const fetched = load?.clearedMessageParts.has(item.id)
-        ? []
-        : item.part.filter((part) => !SKIP_PARTS.has(part.type))
+      const fetched = present(
+        item.id,
+        load?.clearedMessageParts.has(item.id) ? [] : item.part.filter((part) => !SKIP_PARTS.has(part.type)),
+      )
       const fetchedIDs = new Set(fetched.map((part) => part.id))
       const pending = pendingParts.get(sessionID)?.get(item.id)
       const touched = new Set([...(load?.touchedParts.get(item.id) ?? []), ...(pending ?? [])])
@@ -651,25 +570,37 @@ export function createServerSession(
     preserveUnfetched: boolean | ((message: Message) => boolean),
     cleanupOrphans: boolean,
   ) => {
+    if (page.sourceMode === "latest")
+      messageSnapshots.set(sessionID, new Set((page.source ?? []).map((message) => message.id)))
+    page.source?.forEach((message) => releaseEcho(sessionID, message.id))
     const source = page.source
       ? (() => {
           const incoming = new Map(page.source.map((message) => [message.id, message]))
           const existing = data.session_message[sessionID] ?? []
           const boundary = Math.min(...page.source.map((message) => message.time.created))
+          const inbox = new Set(data.input[sessionID] ?? [])
           const current = existing.filter(
             (message) =>
               !incoming.has(message.id) &&
+              !inbox.has(message.id) &&
               (page.sourceMode === "older" ||
                 load?.touchedSource.has(message.id) ||
                 (!page.complete && message.time.created < boundary)),
           )
+          // message.list never returns admitted-but-undelivered inbox entries; keep them after the
+          // fetched history until a delivered or cancelled event resolves them.
+          const admitted = existing.filter((message) => !incoming.has(message.id) && inbox.has(message.id))
+          const combined =
+            page.sourceMode === "older"
+              ? [...page.source, ...current, ...admitted]
+              : [...current, ...page.source, ...admitted]
           const live = new Map(existing.map((message) => [message.id, message]))
-          return (page.sourceMode === "older" ? [...page.source, ...current] : [...current, ...page.source]).map(
-            (message) => (load?.touchedSource.has(message.id) ? (live.get(message.id) ?? message) : message),
+          return combined.map((message) =>
+            load?.touchedSource.has(message.id) ? (live.get(message.id) ?? message) : message,
           )
         })()
       : undefined
-    const projected =
+    const merged =
       page.projectSource && source
         ? (() => {
             const normalized = normalizeSessionMessages(sessionID, source)
@@ -682,16 +613,15 @@ export function createServerSession(
             }
           })()
         : page
-    const merged = mergeOptimisticPage(projected, [...(optimistic.get(sessionID)?.values() ?? [])])
-    merged.observed.forEach((item) => {
-      if (!load?.clearedMessageParts.has(item.messageID)) confirmOptimistic(sessionID, item.messageID, item.parts)
-    })
     const touchedMessages = new Set([...(load?.touchedMessages ?? []), ...(removedMessages.get(sessionID) ?? [])])
     const messages = reconcileFetched(merged.session, data.message[sessionID] ?? [], {
       touched: touchedMessages,
       retained: load?.retainedMessages,
       removed: load?.removedMessages,
-      preserveUnfetched,
+      preserveUnfetched: (message) =>
+        echoes.get(sessionID)?.has(message.id) === true ||
+        preserveUnfetched === true ||
+        (typeof preserveUnfetched === "function" && preserveUnfetched(message)),
       compare: compareMessages,
     })
     batch(() => {
@@ -723,7 +653,6 @@ export function createServerSession(
       deltaParts: new Map(),
       carriedDeltaParts: new Map(),
       removedParts: new Map(),
-      optimisticParts: new Map(),
       orphanParents: new Set(),
       clearedMessageParts: new Set(),
       touchedSource: new Set(),
@@ -744,11 +673,7 @@ export function createServerSession(
         const users = new Set([
           ...page.session.filter((message) => message.role === "user").map((message) => message.id),
           ...(data.message[sessionID] ?? [])
-            .filter((message) => {
-              if (message.role !== "user") return false
-              const item = optimistic.get(sessionID)?.get(message.id)
-              return load.touchedMessages.has(message.id) && (!item || item.confirmedMessage === true)
-            })
+            .filter((message) => message.role === "user" && load.touchedMessages.has(message.id))
             .map((message) => message.id),
         ])
         const parentIDs = [
@@ -893,7 +818,7 @@ export function createServerSession(
         apply({ type: "message.updated", properties: { sessionID: reduction.sessionID, info: message } })
       }
       for (const messageID of touched) {
-        const next = normalized.parts.get(messageID) ?? []
+        const next = present(messageID, normalized.parts.get(messageID) ?? [])
         const nextIDs = new Set(next.map((part) => part.id))
         for (const part of next) {
           apply({ type: "message.part.updated", properties: { sessionID: reduction.sessionID, part } })
@@ -926,6 +851,67 @@ export function createServerSession(
       .catch(() => {})
   }
 
+  const removeEcho = (sessionID: string, messageID: string) => {
+    if (!releaseEcho(sessionID, messageID)) return false
+    pendingRevision.set(sessionID, (pendingRevision.get(sessionID) ?? 0) + 1)
+    const load = messageLoads.get(sessionID)
+    load?.touchedMessages.add(messageID)
+    load?.removedMessages.add(messageID)
+    load?.clearedMessageParts.add(messageID)
+    batch(() => {
+      setData("pending", sessionID, (items) => items?.filter((item) => item.id !== messageID))
+      setData("input", sessionID, (items) => items?.filter((id) => id !== messageID))
+      setData("message", sessionID, (messages) => messages?.filter((message) => message.id !== messageID))
+      setData(produce((draft) => deleteMessageParts(draft, messageID)))
+    })
+    return true
+  }
+
+  const confirmInbox = (item: SessionInboxInfo) => {
+    if (!confirmEcho(item.sessionID, item.id)) return false
+    v2.confirm(item)
+    pendingRevision.set(item.sessionID, (pendingRevision.get(item.sessionID) ?? 0) + 1)
+    const current = data.pending[item.sessionID] ?? []
+    const index = current.findIndex((entry) => entry.id === item.id)
+    if (index < 0) setData("pending", item.sessionID, [...current, item])
+    if (index >= 0) setData("pending", item.sessionID, index, reconcile(item))
+    return true
+  }
+
+  const reconcileInbox = (sessionID: string) => {
+    const pending = new Set((data.pending[sessionID] ?? []).map((item) => item.id))
+    const fetched = messageSnapshots.get(sessionID) ?? new Set<string>()
+    const removed = [...(settledInputs.get(sessionID) ?? [])].filter(
+      (messageID) => !pending.has(messageID) && !fetched.has(messageID),
+    )
+    settledInputs.delete(sessionID)
+    if (removed.length) {
+      const ids = new Set(removed)
+      const source = data.session_message[sessionID] ?? []
+      projectV2({
+        sessionID,
+        messages: source.filter((message) => !ids.has(message.id)),
+        touched: [],
+        removed: source.filter((message) => ids.has(message.id)).map((message) => message.id),
+      })
+    }
+
+    const messages = echoes.get(sessionID)
+    if (!messages) return
+    const projected = new Set((data.session_message[sessionID] ?? []).map((message) => message.id))
+    for (const [messageID, state] of messages) {
+      if (projected.has(messageID)) {
+        releaseEcho(sessionID, messageID)
+        continue
+      }
+      if (pending.has(messageID)) {
+        confirmEcho(sessionID, messageID)
+        continue
+      }
+      if (state === "admitted") removeEcho(sessionID, messageID)
+    }
+  }
+
   const applyV2 = (event: OpenCodeEvent) => {
     if (event.type === "form.created") {
       formRevision.set(event.data.form.sessionID, (formRevision.get(event.data.form.sessionID) ?? 0) + 1)
@@ -949,6 +935,9 @@ export function createServerSession(
     }
     if (!("data" in event) || !("sessionID" in event.data) || typeof event.data.sessionID !== "string") return
     const sessionID = event.data.sessionID
+    if (event.type === "session.inbox.enqueued" || event.type === "session.inbox.delivered")
+      releaseEcho(sessionID, event.data.inboxID)
+    if (event.type === "session.inbox.cancelled") removeEcho(sessionID, event.data.inboxID)
     if (
       event.type === "session.inbox.enqueued" ||
       event.type === "session.inbox.delivery.changed" ||
@@ -960,11 +949,10 @@ export function createServerSession(
       pendingRevision.set(sessionID, (pendingRevision.get(sessionID) ?? 0) + 1)
     if (event.type === "session.inbox.enqueued") {
       const current = data.pending[sessionID] ?? []
-      if (!current.some((item) => item.id === event.data.inboxID))
-        setData("pending", sessionID, [
-          ...current,
-          { id: event.data.inboxID, sessionID, timeCreated: event.created, ...event.data.item },
-        ])
+      const item = { id: event.data.inboxID, sessionID, timeCreated: event.created, ...event.data.item }
+      const index = current.findIndex((entry) => entry.id === event.data.inboxID)
+      if (index < 0) setData("pending", sessionID, [...current, item])
+      if (index >= 0) setData("pending", sessionID, index, reconcile(item))
       if (event.data.item.type !== "compaction" && !data.input[sessionID]?.includes(event.data.inboxID))
         setData("input", sessionID, [...(data.input[sessionID] ?? []), event.data.inboxID])
     }
@@ -1101,16 +1089,9 @@ export function createServerSession(
       }
       case "message.updated": {
         const info = (event.properties as { info: Message }).info
-        indexProjectedMessage(info)
         const load = messageLoads.get(info.sessionID)
         load?.touchedMessages.add(info.id)
         load?.removedMessages.delete(info.id)
-        const items = optimistic.get(info.sessionID)
-        const item = items?.get(info.id)
-        if (items && item) {
-          if (item.parts.length === 0) clearOptimistic(info.sessionID, info.id)
-          if (item.parts.length > 0) items.set(info.id, { ...item, confirmedMessage: true })
-        }
         const orphans = orphanParts.get(info.sessionID)
         orphans?.delete(info.id)
         if (orphans?.size === 0) orphanParts.delete(info.sessionID)
@@ -1123,13 +1104,18 @@ export function createServerSession(
           return
         }
         const result = Binary.search(messages, messageKey(info), messageKey)
-        if (result.found) setData("message", info.sessionID, result.index, reconcile(info))
-        if (!result.found)
-          setData("message", info.sessionID, (value = []) => {
-            const next = value.slice()
-            next.splice(result.index, 0, info)
-            return next
-          })
+        if (result.found) {
+          setData("message", info.sessionID, result.index, reconcile(info))
+          return
+        }
+        // Delivery rewrites time.created, changing the sort key; reposition instead of duplicating.
+        setData("message", info.sessionID, (value = []) => {
+          const next = value.slice()
+          const moved = next.findIndex((message) => message.id === info.id)
+          if (moved >= 0) next.splice(moved, 1)
+          next.splice(moved >= 0 && moved < result.index ? result.index - 1 : result.index, 0, info)
+          return next
+        })
         return
       }
       case "message.removed": {
@@ -1144,13 +1130,11 @@ export function createServerSession(
         load?.deltaParts.delete(props.messageID)
         load?.carriedDeltaParts.delete(props.messageID)
         load?.removedParts.delete(props.messageID)
-        load?.optimisticParts.delete(props.messageID)
         pendingParts.get(props.sessionID)?.delete(props.messageID)
         if (pendingParts.get(props.sessionID)?.size === 0) pendingParts.delete(props.sessionID)
         const removedMessagesForSession = removedMessages.get(props.sessionID) ?? new Set<string>()
         removedMessagesForSession.add(props.messageID)
         removedMessages.set(props.sessionID, removedMessagesForSession)
-        clearOptimistic(props.sessionID, props.messageID)
         setData(
           produce((draft) => {
             const messages = draft.message[props.sessionID]
@@ -1196,12 +1180,8 @@ export function createServerSession(
         pending?.delete(part.id)
         if (pending?.size === 0) pendingParts.get(part.sessionID)?.delete(part.messageID)
         if (pendingParts.get(part.sessionID)?.size === 0) pendingParts.delete(part.sessionID)
-        const optimistic = load?.optimisticParts.get(part.messageID)
-        optimistic?.delete(part.id)
-        if (optimistic?.size === 0) load?.optimisticParts.delete(part.messageID)
         deltaBases.delete(part.id)
         trackPartChange(part.sessionID, part.messageID, part.id)
-        confirmOptimisticPart(part.sessionID, part.messageID, part)
         setData(
           "part_text_accum_delta",
           produce((draft) => void delete draft[part.id]),
@@ -1240,12 +1220,8 @@ export function createServerSession(
           const parts = load.removedParts.get(props.messageID) ?? new Set<string>()
           parts.add(props.partID)
           load.removedParts.set(props.messageID, parts)
-          const optimistic = load.optimisticParts.get(props.messageID)
-          optimistic?.delete(props.partID)
-          if (optimistic?.size === 0) load.optimisticParts.delete(props.messageID)
         }
         trackPartChange(props.sessionID, props.messageID, props.partID)
-        clearOptimisticPart(props.sessionID, props.messageID, props.partID)
         setData(
           produce((draft) => {
             delete draft.part_text_accum_delta[props.partID]
@@ -1354,25 +1330,30 @@ export function createServerSession(
       while (true) {
         const pendingAt = pendingRevision.get(sessionID) ?? 0
         const formAt = formRevision.get(sessionID) ?? 0
+        const previous = new Set(data.input[sessionID] ?? [])
         const result = await load()
         const pendingStable = (pendingRevision.get(sessionID) ?? 0) === pendingAt
         const formStable = (formRevision.get(sessionID) ?? 0) === formAt
         if (pendingStable) {
+          const current = new Set(result.pending.filter((item) => item.type !== "compaction").map((item) => item.id))
+          const settled = settledInputs.get(sessionID) ?? new Set<string>()
+          previous.forEach((messageID) => {
+            if (!current.has(messageID)) settled.add(messageID)
+          })
+          if (settled.size) settledInputs.set(sessionID, settled)
+          result.pending.forEach(v2.confirm)
           setData("pending", sessionID, reconcile(result.pending))
-          setData(
-            "input",
-            sessionID,
-            reconcile(result.pending.filter((item) => item.type !== "compaction").map((item) => item.id)),
-          )
+          setData("input", sessionID, reconcile([...current]))
         }
         if (formStable) setData("form", sessionID, reconcile(result.forms))
         if (pendingStable && formStable) return
       }
     },
     refreshPinned(hydrateTransient: (sessionID: string) => Promise<void>) {
+      const sessions = [...pinned.keys()]
       return Promise.all(
-        [...pinned.keys()].flatMap((sessionID) => [sync(sessionID, { force: true }), hydrateTransient(sessionID)]),
-      ).then(() => undefined)
+        sessions.flatMap((sessionID) => [sync(sessionID, { force: true }), hydrateTransient(sessionID)]),
+      ).then(() => sessions.forEach(reconcileInbox))
     },
     invalidate() {
       invalidationRevision += 1
@@ -1390,68 +1371,72 @@ export function createServerSession(
     fresh(sessionID: string, ttl: number) {
       return Date.now() - (meta.at[sessionID] ?? 0) <= ttl
     },
-    optimistic: {
-      add(input: { sessionID: string; message: Message; parts: Part[] }) {
-        const parts = input.parts
-          .filter((part) => !!part?.id && !SKIP_PARTS.has(part.type))
-          .sort((a, b) => cmp(a.id, b.id))
-        const load = messageLoads.get(input.sessionID)
-        if (load?.clearedMessageParts.has(input.message.id)) {
-          const touched = load.touchedParts.get(input.message.id) ?? new Set<string>()
-          parts.forEach((part) => touched.add(part.id))
-          load.touchedParts.set(input.message.id, touched)
+    inbox: {
+      echo(input: PromptEcho) {
+        const created = Date.now()
+        const files = input.files?.map((file) => ({
+          data: "",
+          mime: file.mime,
+          source: { type: "uri" as const, uri: file.uri },
+          name: file.name,
+          mention: file.mention,
+        }))
+        const item: SessionInboxInfo = {
+          id: input.messageID,
+          sessionID: input.sessionID,
+          timeCreated: created,
+          type: "user",
+          delivery: "steer",
+          payload: { text: input.text, files, agents: input.agents },
         }
-        if (load) {
-          load.removedMessages.delete(input.message.id)
-          load.optimisticParts.set(input.message.id, new Set(parts.map((part) => part.id)))
-        }
-        const items = optimistic.get(input.sessionID)
-        const removedMessagesForSession = removedMessages.get(input.sessionID)
-        removedMessagesForSession?.delete(input.message.id)
-        if (removedMessagesForSession?.size === 0) removedMessages.delete(input.sessionID)
-        if (items) items.set(input.message.id, { ...input, parts, confirmedParts: [] })
-        if (!items)
-          optimistic.set(input.sessionID, new Map([[input.message.id, { ...input, parts, confirmedParts: [] }]]))
-        indexProjectedMessage(input.message)
-        setData("message", input.sessionID, (messages = []) => merge(messages, [input.message]).sort(compareMessages))
-        setData(
-          "part_text_accum_delta",
-          produce((draft) => {
-            for (const part of [...(data.part[input.message.id] ?? []), ...parts]) {
-              delete draft[part.id]
-              deltaBases.delete(part.id)
-            }
-          }),
-        )
-        setData("part", input.message.id, parts)
+        const projected = normalizeSessionMessages(input.sessionID, [
+          { id: `${input.messageID}:agent`, type: "agent-switched", agent: input.agent, time: { created } },
+          {
+            id: `${input.messageID}:model`,
+            type: "model-switched",
+            model: {
+              id: input.model.modelID,
+              providerID: input.model.providerID,
+              variant: input.model.variant,
+            },
+            time: { created },
+          },
+          {
+            id: input.messageID,
+            type: "user",
+            text: input.displayText,
+            files,
+            agents: input.agents,
+            time: { created },
+          },
+        ])
+        const message = projected.messages[0]!
+        const comments: Part[] = input.comments.map((comment, index) => ({
+          id: `${input.messageID}:comment:${index}`,
+          sessionID: input.sessionID,
+          messageID: input.messageID,
+          type: "text",
+          text: formatCommentNote(comment),
+          synthetic: true,
+          metadata: createCommentMetadata(comment),
+        }))
+        const parts = merge(projected.parts.get(input.messageID) ?? [], comments).sort((a, b) => cmp(a.id, b.id))
+        removedMessages.get(input.sessionID)?.delete(input.messageID)
+        markEcho(input.sessionID, input.messageID)
+        pendingRevision.set(input.sessionID, (pendingRevision.get(input.sessionID) ?? 0) + 1)
+        batch(() => {
+          setData("pending", input.sessionID, (items = []) => [...items.filter((entry) => entry.id !== item.id), item])
+          if (!data.input[input.sessionID]?.includes(input.messageID))
+            setData("input", input.sessionID, [...(data.input[input.sessionID] ?? []), input.messageID])
+          setData("message", input.sessionID, (messages = []) => merge(messages, [message]).sort(compareMessages))
+          setData("part", input.messageID, parts)
+        })
       },
-      remove(input: { sessionID: string; messageID: string }) {
-        const item = optimistic.get(input.sessionID)?.get(input.messageID)
-        if (!item) return
-        messageLoads.get(input.sessionID)?.optimisticParts.delete(input.messageID)
-        clearOptimistic(input.sessionID, input.messageID)
-        if (item.confirmedMessage) {
-          const partIDs = new Set(item.parts.map((part) => part.id))
-          setData(
-            produce((draft) => {
-              for (const part of item.parts) {
-                delete draft.part_text_accum_delta[part.id]
-                deltaBases.delete(part.id)
-              }
-              const parts = draft.part[input.messageID]
-              if (!parts) return
-              draft.part[input.messageID] = parts.filter((part) => !partIDs.has(part.id))
-              if (draft.part[input.messageID]?.length === 0) delete draft.part[input.messageID]
-            }),
-          )
-          return
-        }
-        const projectedIDs = new Set(projectMessageSource(item.message).map((message) => message.id))
-        setData("session_message", input.sessionID, (messages) =>
-          messages?.filter((message) => !projectedIDs.has(message.id)),
-        )
-        setData("message", input.sessionID, (messages) => messages?.filter((message) => message.id !== input.messageID))
-        setData(produce((draft) => deleteMessageParts(draft, input.messageID)))
+      confirm: confirmInbox,
+      reconcile: reconcileInbox,
+      clearEcho(input: { sessionID: string; messageID: string }) {
+        if (echoes.get(input.sessionID)?.get(input.messageID) !== "sending") return false
+        return removeEcho(input.sessionID, input.messageID)
       },
     },
     async todo(sessionID: string, request?: { force?: boolean }) {
diff --git a/packages/app/src/context/server-sync.tsx b/packages/app/src/context/server-sync.tsx
index 16c085cf5f2..e4befa5a521 100644
--- a/packages/app/src/context/server-sync.tsx
+++ b/packages/app/src/context/server-sync.tsx
@@ -231,7 +231,10 @@ export function createServerSyncContextInner(serverSDK: ServerSDK) {
       return { pending, forms }
     })
   }
-  const hydrateSession = (sessionID: string) => Promise.all([session.sync(sessionID), hydrateSessionState(sessionID)])
+  const hydrateSession = async (sessionID: string) => {
+    await Promise.all([session.sync(sessionID), hydrateSessionState(sessionID)])
+    session.inbox.reconcile(sessionID)
+  }
 
   const [configQuery, providerQuery, pathQuery] = useQueries(() => ({
     queries: [
diff --git a/packages/app/src/context/sync-optimistic.test.ts b/packages/app/src/context/sync-optimistic.test.ts
deleted file mode 100644
index 15adcf441a3..00000000000
--- a/packages/app/src/context/sync-optimistic.test.ts
+++ /dev/null
@@ -1,137 +0,0 @@
-import { describe, expect, test } from "bun:test"
-import type { Message, Part } from "@/types"
-import { applyOptimisticAdd, applyOptimisticRemove, mergeOptimisticPage } from "./sync"
-
-type Text = Extract<Part, { type: "text" }>
-
-const userMessage = (id: string, sessionID: string, created = 1): Message => ({
-  id,
-  sessionID,
-  role: "user",
-  time: { created },
-  agent: "assistant",
-  model: { providerID: "openai", modelID: "gpt" },
-})
-
-const textPart = (id: string, sessionID: string, messageID: string): Text => ({
-  id,
-  sessionID,
-  messageID,
-  type: "text",
-  text: id,
-})
-
-describe("sync optimistic reducers", () => {
-  test("applyOptimisticAdd inserts by creation time", () => {
-    const sessionID = "ses_1"
-    const draft = {
-      message: { [sessionID]: [userMessage("msg_z", sessionID, 1)] },
-      part: {} as Record<string, Part[] | undefined>,
-    }
-
-    applyOptimisticAdd(draft, {
-      sessionID,
-      message: userMessage("msg_a", sessionID, 2),
-      parts: [textPart("prt_2", sessionID, "msg_a"), textPart("prt_1", sessionID, "msg_a")],
-    })
-
-    expect(draft.message[sessionID]?.map((x) => x.id)).toEqual(["msg_z", "msg_a"])
-    expect(draft.part.msg_a?.map((x) => x.id)).toEqual(["prt_1", "prt_2"])
-  })
-
-  test("applyOptimisticRemove removes message and part entries", () => {
-    const sessionID = "ses_1"
-    const draft = {
-      message: { [sessionID]: [userMessage("msg_1", sessionID), userMessage("msg_2", sessionID)] },
-      part: {
-        msg_1: [textPart("prt_1", sessionID, "msg_1")],
-        msg_2: [textPart("prt_2", sessionID, "msg_2")],
-      } as Record<string, Part[] | undefined>,
-    }
-
-    applyOptimisticRemove(draft, { sessionID, messageID: "msg_1" })
-
-    expect(draft.message[sessionID]?.map((x) => x.id)).toEqual(["msg_2"])
-    expect(draft.part.msg_1).toBeUndefined()
-    expect(draft.part.msg_2).toHaveLength(1)
-  })
-
-  test("mergeOptimisticPage keeps pending messages in fetched timelines", () => {
-    const sessionID = "ses_1"
-    const page = mergeOptimisticPage(
-      {
-        session: [userMessage("msg_z", sessionID, 1)],
-        part: [{ id: "msg_z", part: [textPart("prt_1", sessionID, "msg_z")] }],
-        complete: true,
-      },
-      [{ message: userMessage("msg_a", sessionID, 2), parts: [textPart("prt_2", sessionID, "msg_a")] }],
-    )
-
-    expect(page.session.map((x) => x.id)).toEqual(["msg_z", "msg_a"])
-    expect(page.part.find((x) => x.id === "msg_a")?.part.map((x) => x.id)).toEqual(["prt_2"])
-    expect(page.confirmed).toEqual([])
-    expect(page.complete).toBe(true)
-  })
-
-  test("mergeOptimisticPage uses IDs only to break equal-time ties", () => {
-    const sessionID = "ses_1"
-    const page = mergeOptimisticPage(
-      {
-        session: [userMessage("msg_z", sessionID, 1)],
-        part: [],
-        complete: true,
-      },
-      [{ message: userMessage("msg_a", sessionID, 1), parts: [] }],
-    )
-
-    expect(page.session.map((message) => message.id)).toEqual(["msg_a", "msg_z"])
-  })
-
-  test("mergeOptimisticPage keeps missing optimistic parts until the server has them", () => {
-    const sessionID = "ses_1"
-    const page = mergeOptimisticPage(
-      {
-        session: [userMessage("msg_2", sessionID)],
-        part: [{ id: "msg_2", part: [textPart("prt_2", sessionID, "msg_2")] }],
-        complete: true,
-      },
-      [
-        {
-          message: userMessage("msg_2", sessionID),
-          parts: [textPart("prt_1", sessionID, "msg_2"), textPart("prt_2", sessionID, "msg_2")],
-        },
-      ],
-    )
-
-    expect(page.part.find((x) => x.id === "msg_2")?.part.map((x) => x.id)).toEqual(["prt_1", "prt_2"])
-    expect(page.confirmed).toEqual([])
-  })
-
-  test("mergeOptimisticPage confirms echoed messages once all parts arrive", () => {
-    const sessionID = "ses_1"
-    const page = mergeOptimisticPage(
-      {
-        session: [userMessage("msg_2", sessionID)],
-        part: [
-          {
-            id: "msg_2",
-            part: [{ ...textPart("prt_1", sessionID, "msg_2"), text: "server" }, textPart("prt_2", sessionID, "msg_2")],
-          },
-        ],
-        complete: true,
-      },
-      [
-        {
-          message: userMessage("msg_2", sessionID),
-          parts: [textPart("prt_1", sessionID, "msg_2"), textPart("prt_2", sessionID, "msg_2")],
-        },
-      ],
-    )
-
-    expect(page.confirmed).toEqual(["msg_2"])
-    expect(page.part.find((x) => x.id === "msg_2")?.part).toMatchObject([
-      { id: "prt_1", type: "text", text: "server" },
-      { id: "prt_2", type: "text", text: "prt_2" },
-    ])
-  })
-})
diff --git a/packages/app/src/context/sync.tsx b/packages/app/src/context/sync.tsx
index d8adf6a14b6..813c5698fd5 100644
--- a/packages/app/src/context/sync.tsx
+++ b/packages/app/src/context/sync.tsx
@@ -1,114 +1,6 @@
-import { Binary } from "@opencode-ai/core/util/binary"
 import { createMemo } from "solid-js"
 import { useServerSync } from "./server-sync"
 import { useSDK } from "./sdk"
-import type { Message, Part } from "@/types"
-import { messageKey } from "@/utils/session-message"
-
-const SKIP_PARTS = new Set(["patch", "step-start", "step-finish"])
-
-function sortParts(parts: Part[]) {
-  return parts.filter((part) => !!part?.id).sort((a, b) => cmp(a.id, b.id))
-}
-
-const cmp = (a: string, b: string) => (a < b ? -1 : a > b ? 1 : 0)
-
-type OptimisticStore = {
-  message: Record<string, Message[] | undefined>
-  part: Record<string, Part[] | undefined>
-}
-
-type OptimisticAddInput = {
-  sessionID: string
-  message: Message
-  parts: Part[]
-}
-
-type OptimisticRemoveInput = {
-  sessionID: string
-  messageID: string
-}
-
-type OptimisticItem = {
-  message: Message
-  parts: Part[]
-}
-
-type MessagePage = {
-  session: Message[]
-  part: { id: string; part: Part[] }[]
-  cursor?: string
-  complete: boolean
-}
-
-const hasParts = (parts: Part[] | undefined, want: Part[]) => {
-  if (!parts) return want.length === 0
-  return want.every((part) => Binary.search(parts, part.id, (item) => item.id).found)
-}
-
-const mergeParts = (parts: Part[] | undefined, want: Part[]) => {
-  if (!parts) return sortParts(want)
-  const next = [...parts]
-  let changed = false
-  for (const part of want) {
-    const result = Binary.search(next, part.id, (item) => item.id)
-    if (result.found) continue
-    next.splice(result.index, 0, part)
-    changed = true
-  }
-  if (!changed) return parts
-  return next
-}
-
-export function mergeOptimisticPage(page: MessagePage, items: OptimisticItem[]) {
-  if (items.length === 0) return { ...page, confirmed: [] as string[] }
-
-  const session = [...page.session]
-  const part = new Map(page.part.map((item) => [item.id, sortParts(item.part)]))
-  const confirmed: string[] = []
-
-  for (const item of items) {
-    const result = Binary.search(session, messageKey(item.message), messageKey)
-    const found = result.found
-    if (!found) session.splice(result.index, 0, item.message)
-
-    const current = part.get(item.message.id)
-    if (found && hasParts(current, item.parts)) {
-      confirmed.push(item.message.id)
-      continue
-    }
-
-    part.set(item.message.id, mergeParts(current, item.parts))
-  }
-
-  return {
-    cursor: page.cursor,
-    complete: page.complete,
-    session,
-    part: [...part.entries()].sort((a, b) => cmp(a[0], b[0])).map(([id, part]) => ({ id, part })),
-    confirmed,
-  }
-}
-
-export function applyOptimisticAdd(draft: OptimisticStore, input: OptimisticAddInput) {
-  const messages = draft.message[input.sessionID]
-  if (messages) {
-    const result = Binary.search(messages, messageKey(input.message), messageKey)
-    messages.splice(result.index, 0, input.message)
-  } else {
-    draft.message[input.sessionID] = [input.message]
-  }
-  draft.part[input.message.id] = sortParts(input.parts)
-}
-
-export function applyOptimisticRemove(draft: OptimisticStore, input: OptimisticRemoveInput) {
-  const messages = draft.message[input.sessionID]
-  if (messages) {
-    const index = messages.findIndex((message) => message.id === input.messageID)
-    if (index >= 0) messages.splice(index, 1)
-  }
-  delete draft.part[input.messageID]
-}
 
 export const useSync = () => {
   const serverSync = useServerSync()