chore: enforce effect simplifications (#43979)

.github/workflows/test.yml

@@ -50,6 +50,14 @@ jobs:
       - name: Setup Bun
         uses: ./.github/actions/setup-bun
 
+      - name: Test Effect simplification rules
+        if: runner.os == 'Linux'
+        run: bun run test:effect-simplification-rules
+
+      - name: Check Effect simplifications
+        if: runner.os == 'Linux'
+        run: bun run lint:effect-simplifications
+
       - name: Configure git identity
         run: |
           git config --global user.email "bot@opencode.ai"

package.json

@@ -18,7 +18,9 @@
     "bench:devex": "bun run --cwd packages/app test:bench:devex",
     "lint": "oxlint",
     "lint:effect-patterns": "ast-grep scan -c script/ast-grep/sgconfig.yml packages/util/src packages/core/src packages/server/src packages/protocol/src packages/cli/src",
+    "lint:effect-simplifications": "ast-grep scan -c script/ast-grep/effect-simplifications/sgconfig.yml --off=unused-suppression packages",
     "test:lint-rules": "ast-grep test -c script/ast-grep/sgconfig.yml",
+    "test:effect-simplification-rules": "ast-grep test -c script/ast-grep/effect-simplifications/sgconfig.yml",
     "typecheck": "bun turbo typecheck --concurrency=3",
     "typecheck:profile": "bun script/profile-typecheck.ts",
     "typecheck:profile:packages": "bun script/profile-typecheck-packages.ts",

packages/ai/script/setup-recording-env.ts

@@ -370,7 +370,7 @@ const responseError = Effect.fn("RecordingEnv.responseError")(function* (
   response: HttpClientResponse.HttpClientResponse,
 ) {
   if (response.status >= 200 && response.status < 300) return undefined
-  const body = yield* response.text.pipe(Effect.catch(() => Effect.succeed("")))
+  const body = yield* response.text.pipe(Effect.orElseSucceed(() => ""))
   return `${response.status}${body ? `: ${body.slice(0, 180)}` : ""}`
 })
 

packages/cli/src/config/config.ts

@@ -31,7 +31,7 @@ export const layer = Layer.effect(
     const file = path.join(global.config, "cli.json")
 
     const readJson = Effect.fnUntraced(function* () {
-      const text = yield* fs.readFileString(file).pipe(Effect.catch(() => Effect.succeed(undefined)))
+      const text = yield* fs.readFileString(file).pipe(Effect.orElseSucceed(() => undefined))
       if (text === undefined) return undefined
       const errors: ParseError[] = []
       const value: any = parse(text, errors, { allowTrailingComma: true })
@@ -87,7 +87,7 @@ export const layer = Layer.effect(
           const next = produce(current, update)
           const edits = changes(current, next)
           if (!edits.length) return current
-          const text = yield* fs.readFileString(file).pipe(Effect.catch(() => Effect.succeed("{}")))
+          const text = yield* fs.readFileString(file).pipe(Effect.orElseSucceed(() => "{}"))
           const updated = edits.reduce(
             (text, edit) =>
               applyEdits(

packages/cli/src/config/migrate.ts

@@ -258,7 +258,7 @@ export function migrateV1(legacy: TuiConfigV1.Info | undefined, kv: Record<strin
 
 const readJson = Effect.fnUntraced(function* (target: string) {
   const fs = yield* FileSystem.FileSystem
-  const text = yield* fs.readFileString(target).pipe(Effect.catch(() => Effect.succeed(undefined)))
+  const text = yield* fs.readFileString(target).pipe(Effect.orElseSucceed(() => undefined))
   if (text === undefined) return undefined
   const errors: ParseError[] = []
   const value: any = parse(text, errors, { allowTrailingComma: true })

packages/cli/src/services/service-config.ts

@@ -119,7 +119,7 @@ export const read = Effect.fn("cli.service-config.read")(function* () {
   if (legacyConfigFile) yield* migrateConfig(legacyConfigFile, configFile)
   return yield* fs.readFileString(configFile).pipe(
     Effect.flatMap(decodeInfo),
-    Effect.catch(() => Effect.succeed({} as Info)),
+    Effect.orElseSucceed(() => ({}) as Info),
   )
 })
 

packages/cli/src/services/updater.ts

@@ -44,7 +44,7 @@ export const layer = Layer.effect(
       const values = yield* Effect.forEach(["config.json", "opencode.json", "opencode.jsonc"], (name) =>
         fs.readFileString(path.join(global.config, name)).pipe(
           Effect.map(decodePolicy),
-          Effect.catch(() => Effect.succeed(undefined)),
+          Effect.orElseSucceed(() => undefined),
         ),
       )
       return values.findLast((value) => value !== undefined) ?? true
@@ -63,7 +63,7 @@ export const layer = Layer.effect(
             stdout: result.stdout.toString("utf8"),
             stderr: result.stderr.toString("utf8"),
           })),
-          Effect.catch(() => Effect.succeed({ code: 1, stdout: "", stderr: "" })),
+          Effect.orElseSucceed(() => ({ code: 1, stdout: "", stderr: "" })),
         )
     })
 

packages/core/src/config.ts

@@ -347,7 +347,7 @@ export const layer = (options?: Options) =>
         Stream.filterEffect((event) =>
           wellknown.entries().pipe(
             Effect.map((entries) => entries.some((entry) => entry.integrationID === event.data.integrationID)),
-            Effect.catch(() => Effect.succeed(false)),
+            Effect.orElseSucceed(() => false),
           ),
         ),
         Stream.runForEach(() =>

packages/core/src/config/plugin/agent.ts

@@ -59,7 +59,7 @@ export const Plugin = define({
       return yield* Effect.forEach(files, (file) =>
         fs.readFileStringSafe(file.filepath).pipe(
           Effect.map((content) => (content ? decode(file, content) : undefined)),
-          Effect.catch(() => Effect.succeed(undefined)),
+          Effect.orElseSucceed(() => undefined),
         ),
       ).pipe(Effect.map((documents) => documents.filter((document): document is Document => document !== undefined)))
     })
@@ -176,7 +176,7 @@ function discover(fs: FSUtil.Interface, directory: string) {
       ),
   ).pipe(
     Effect.map((files) => files.flat()),
-    Effect.catch(() => Effect.succeed([])),
+    Effect.orElseSucceed(() => []),
   )
 }
 

packages/core/src/config/plugin/command.ts

@@ -86,11 +86,11 @@ function loadDirectory(fs: FSUtil.Interface, directory: string) {
   return Effect.gen(function* () {
     const files = yield* fs
       .scan("{command,commands}/**/*.md", { cwd: directory, absolute: true, dot: true, symlink: true })
-      .pipe(Effect.catch(() => Effect.succeed([] as string[])))
+      .pipe(Effect.orElseSucceed(() => [] as string[]))
     return yield* Effect.forEach(files.toSorted(), (filepath) =>
       fs.readFileStringSafe(filepath).pipe(
         Effect.map((content) => (content === undefined ? undefined : decode(directory, filepath, content))),
-        Effect.catch(() => Effect.succeed(undefined)),
+        Effect.orElseSucceed(() => undefined),
       ),
     ).pipe(
       Effect.map((commands) =>

packages/core/src/config/plugin/source.ts

@@ -148,7 +148,7 @@ const scan = Effect.fn("ConfigPluginSource.scan")(function* (
         ...operation,
         mtime: Option.getOrElse(info.mtime, () => new Date(0)).getTime(),
       })),
-      Effect.catch(() => Effect.succeed(operation)),
+      Effect.orElseSucceed(() => operation),
     )
   })
 })

packages/core/src/filesystem/location-watcher.ts

@@ -35,14 +35,12 @@ const layer = Layer.effect(
       Effect.gen(function* () {
         if (location.vcs?.type === "git") {
           const resolved = (yield* git.repo.discover(location.directory))?.gitDirectory
-          const vcs = resolved
-            ? yield* fs.realPath(resolved).pipe(Effect.catch(() => Effect.succeed(resolved)))
-            : undefined
+          const vcs = resolved ? yield* fs.realPath(resolved).pipe(Effect.orElseSucceed(() => resolved)) : undefined
           if (vcs) return { path: path.join(vcs, "HEAD"), aliases: [".git", vcs, ...(resolved ? [resolved] : [])] }
         }
         if (location.vcs?.type === "hg") {
           const store = location.vcs.store
-          const vcs = yield* fs.realPath(store).pipe(Effect.catch(() => Effect.succeed(store)))
+          const vcs = yield* fs.realPath(store).pipe(Effect.orElseSucceed(() => store))
           return { path: path.join(vcs, "branch"), aliases: [".hg", vcs] }
         }
       }).pipe(

packages/core/src/models-dev.ts

@@ -622,7 +622,7 @@ export const layer = (options?: Options) =>
       const loadFromFile = options?.file
         ? fs.readJson(options.file).pipe(
             Effect.map((input) => input as Record<string, SourceProvider>),
-            Effect.catch(() => Effect.succeed(undefined)),
+            Effect.orElseSucceed(() => undefined),
           )
         : Effect.succeed(undefined)
 

packages/core/src/plugin/provider/github-copilot.ts

@@ -108,7 +108,7 @@ const oauth = (app: App.Info) =>
                   },
                 ).pipe(
                   Effect.map((user) => Option.getOrUndefined(decodeUser(user))?.endpoints?.api?.replace(/\/+$/, "")),
-                  Effect.catch(() => Effect.succeed(undefined)),
+                  Effect.orElseSucceed(() => undefined),
                   Effect.map((apiEndpoint) =>
                     Credential.OAuth.make({
                       type: "oauth",
@@ -159,7 +159,7 @@ export const GithubCopilotPlugin = define({
     const load = Effect.fn("GithubCopilotPlugin.load")(function* () {
       const connection = yield* ctx.integration.connection.active("github-copilot")
       const credential = connection
-        ? yield* ctx.integration.connection.resolve(connection).pipe(Effect.catch(() => Effect.succeed(undefined)))
+        ? yield* ctx.integration.connection.resolve(connection).pipe(Effect.orElseSucceed(() => undefined))
         : undefined
       if (credential?.type !== "oauth") {
         loaded.baseURL = undefined

packages/core/src/plugin/provider/ollama.ts

@@ -148,7 +148,7 @@ export function make(origin = "http://127.0.0.1:11434", interval: Duration.Input
                         )
                   shows.set(model.model, { digest: model.digest, info })
                   return { ...model, show: info }
-                }).pipe(Effect.catch(() => Effect.succeed(undefined))),
+                }).pipe(Effect.orElseSucceed(() => undefined)),
               { concurrency: 4 },
             )
             const filtered = models.filter(

packages/core/src/plugin/provider/openai.ts

@@ -175,7 +175,7 @@ export const OpenAIPlugin = define({
     const load = Effect.fn("OpenAIPlugin.load")(function* () {
       const connection = yield* ctx.integration.connection.active("openai")
       const credential = connection
-        ? yield* ctx.integration.connection.resolve(connection).pipe(Effect.catch(() => Effect.succeed(undefined)))
+        ? yield* ctx.integration.connection.resolve(connection).pipe(Effect.orElseSucceed(() => undefined))
         : undefined
       chatgpt =
         credential?.type === "oauth" &&

packages/core/src/plugin/provider/opencode.ts

@@ -92,7 +92,7 @@ export const OpencodePlugin = define<HttpClient.HttpClient | Bus.Service | Scope
     const load = Effect.fn("OpencodePlugin.load")(function* () {
       const connection = yield* ctx.integration.connection.active("opencode")
       const credential = connection
-        ? yield* ctx.integration.connection.resolve(connection).pipe(Effect.catch(() => Effect.succeed(undefined)))
+        ? yield* ctx.integration.connection.resolve(connection).pipe(Effect.orElseSucceed(() => undefined))
         : undefined
       connected = connection !== undefined
       providers = credential

packages/core/src/plugin/provider/xai.ts

@@ -144,7 +144,7 @@ function poll(device: typeof Device.Type, app: App.Info): Effect.Effect<Token, u
         if (response.ok) return yield* decode(response, Token)
         const error = yield* Effect.promise(() => response.text()).pipe(
           Effect.map((body) => Option.getOrUndefined(decodeDeviceError(body))),
-          Effect.catch(() => Effect.succeed(undefined)),
+          Effect.orElseSucceed(() => undefined),
         )
         if (error?.error === "authorization_pending") {
           return yield* Effect.sleep(interval + pollingSafetyMargin).pipe(Effect.andThen(loop(interval)))

packages/core/src/project.ts

@@ -41,7 +41,7 @@ export interface Resolved {
 export const root = Effect.fn("Project.root")(function* (fs: FSUtil.Interface, input: AbsolutePath) {
   return yield* fs.up({ targets: [".git", ".hg"], start: input, mode: "first" }).pipe(
     Effect.map((matches) => (matches[0] ? AbsolutePath.make(path.dirname(matches[0])) : undefined)),
-    Effect.catch(() => Effect.succeed(undefined)),
+    Effect.orElseSucceed(() => undefined),
   )
 })
 
@@ -149,7 +149,7 @@ const layer = Layer.effect(
       return yield* fs.readFileString(path.join(dir, "opencode")).pipe(
         Effect.map((value) => value.trim()),
         Effect.map((value) => (value ? ID.make(value) : undefined)),
-        Effect.catch(() => Effect.succeed(undefined)),
+        Effect.orElseSucceed(() => undefined),
       )
     })
 
@@ -202,7 +202,7 @@ const layer = Layer.effect(
             stdin: "ignore",
           }),
         )
-        .pipe(Effect.catch(() => Effect.succeed(undefined)))
+        .pipe(Effect.orElseSucceed(() => undefined))
       if (!result || result.exitCode !== 0) return undefined
       const node = result.stdout
         .toString("utf8")
@@ -216,7 +216,7 @@ const layer = Layer.effect(
     const hgDiscover = Effect.fnUntraced(function* (input: AbsolutePath) {
       const dotHg = yield* fs.up({ targets: [".hg"], start: input, mode: "first" }).pipe(
         Effect.map((matches) => matches[0]),
-        Effect.catch(() => Effect.succeed(undefined)),
+        Effect.orElseSucceed(() => undefined),
       )
       if (!dotHg) return undefined
       const worktree = AbsolutePath.make(path.dirname(dotHg))
@@ -241,7 +241,7 @@ const layer = Layer.effect(
             ? repo.worktree
             : yield* git.worktree.list(repo).pipe(
                 Effect.map((items) => items.find((item) => item.kind === "main")?.directory ?? repo.worktree),
-                Effect.catch(() => Effect.succeed(repo.worktree)),
+                Effect.orElseSucceed(() => repo.worktree),
               )
         return yield* persist({
           previous,

packages/core/src/session.ts

@@ -768,7 +768,7 @@ const layer = Layer.effect(
         const expanded =
           value === "~" ? global.home : value.startsWith("~/") ? path.join(global.home, value.slice(2)) : value
         const directory = AbsolutePath.make(path.resolve(current.location.directory, expanded))
-        const info = yield* fs.stat(directory).pipe(Effect.catch(() => Effect.succeed(undefined)))
+        const info = yield* fs.stat(directory).pipe(Effect.orElseSucceed(() => undefined))
         if (!info) return yield* new DestinationNotFoundError({ directory })
         if (info.type !== "Directory") return yield* new DestinationNotDirectoryError({ directory })
         const project = yield* projects.resolve(directory)
@@ -787,7 +787,7 @@ const layer = Layer.effect(
           input.sessionID,
           Effect.gen(function* () {
             const latest = yield* result.get(input.sessionID)
-            const source = yield* fs.stat(latest.location.directory).pipe(Effect.catch(() => Effect.succeed(undefined)))
+            const source = yield* fs.stat(latest.location.directory).pipe(Effect.orElseSucceed(() => undefined))
             if (!source || source.type !== "Directory") {
               const cancellations = (yield* SessionInbox.moveIDs(db, input.sessionID)).map(
                 (item) => [SessionEvent.InboxCancelled, { sessionID: input.sessionID, inboxID: item.id }] as const,

packages/core/src/session/history.ts

@@ -120,7 +120,7 @@ export const firstUserMessage = Effect.fn("SessionHistory.firstUserMessage")(fun
     .get()
     .pipe(Effect.orDie)
   if (!row) return undefined
-  const message = yield* decodeMessageRow(row).pipe(Effect.catch(() => Effect.succeed(undefined)))
+  const message = yield* decodeMessageRow(row).pipe(Effect.orElseSucceed(() => undefined))
   return message?.type === "user" ? message : undefined
 })
 

packages/core/src/session/model-transport.ts

@@ -319,7 +319,7 @@ export const makeLayer = (connector: WebSocketConnector) =>
                     }).pipe(
                       Effect.andThen(metric("connect_failure")),
                       Effect.andThen(metric("fallback")),
-                      Effect.asVoid,
+                      Effect.as(undefined),
                     ),
               ),
             )

packages/core/src/shell.ts

@@ -77,7 +77,7 @@ export const cleanup = Effect.fn("Shell.cleanup")(function* () {
   const directory = path.join(global.data, DIRECTORY)
   const projects = yield* fs.readDirectoryEntries(directory).pipe(
     Effect.map((entries) => entries.filter((entry) => entry.type === "directory")),
-    Effect.catch(() => Effect.succeed([])),
+    Effect.orElseSucceed(() => []),
   )
   const files = yield* Effect.forEach(
     projects,
@@ -90,7 +90,7 @@ export const cleanup = Effect.fn("Shell.cleanup")(function* () {
               : [],
           ),
         ),
-        Effect.catch(() => Effect.succeed([])),
+        Effect.orElseSucceed(() => []),
       ),
     { concurrency: 8 },
   )

packages/core/src/tool-output.ts

@@ -36,7 +36,7 @@ export class Service extends Context.Service<Service, Interface>()("@opencode/To
 const cleanup = Effect.fn("ToolOutput.cleanup")(function* (fs: FSUtil.Interface, directory: string) {
   const entries = yield* fs.readDirectory(directory).pipe(
     Effect.map((entries) => entries.filter((entry) => /^tool_[0-9a-f]{12}/.test(entry))),
-    Effect.catch(() => Effect.succeed([])),
+    Effect.orElseSucceed(() => []),
   )
   yield* FileRetention.cleanup(
     fs,

packages/core/src/tool/plugin/read.ts

@@ -142,7 +142,7 @@ export const Plugin = {
             .map((entry) => join(dirname(input), entry))
             .slice(0, 3),
         ),
-        Effect.catch(() => Effect.succeed([] as string[])),
+        Effect.orElseSucceed(() => [] as string[]),
       )
       const message =
         suggestions.length === 0

packages/core/src/vcs.ts

@@ -49,7 +49,7 @@ const layer = Layer.effect(
     const state = { info: impl ? yield* impl.info() : ({ branch: {} } satisfies Info) }
 
     if (vcs && impl) {
-      const store = yield* fs.realPath(vcs.store).pipe(Effect.catch(() => Effect.succeed(vcs.store)))
+      const store = yield* fs.realPath(vcs.store).pipe(Effect.orElseSucceed(() => vcs.store))
       const isBranchMetadata =
         vcs.type === "git"
           ? (file: string) => path.basename(file) === "HEAD" && FSUtil.contains(store, file)

packages/core/src/vcs/git.ts

@@ -141,7 +141,7 @@ function makeGit(proc: AppProcess.Interface) {
         truncated: result.stdoutTruncated || result.stderrTruncated,
       }
     },
-    Effect.catch(() => Effect.succeed({ exitCode: 1, text: () => "", truncated: false })),
+    Effect.orElseSucceed(() => ({ exitCode: 1, text: () => "", truncated: false })),
   )
 
   const text = Effect.fnUntraced(function* (args: string[], opts: { cwd: string }) {

packages/core/test/config/websearch.test.ts

@@ -32,7 +32,7 @@ describe("ConfigWebSearchPlugin.Plugin", () => {
       yield* waitUntil(
         websearch.default().pipe(
           Effect.map((provider) => provider?.id === WebSearch.ID.make("test")),
-          Effect.catch(() => Effect.succeed(false)),
+          Effect.orElseSucceed(() => false),
         ),
       )
     }).pipe(Effect.provide(Config.testLayer([configured(false)]))),

packages/core/test/effect-simplification-types.test.ts

@@ -0,0 +1,12 @@
+import { expect, test } from "bun:test"
+import { Effect } from "effect"
+
+const source = Effect.succeed(1)
+const exactUndefined: Effect.Effect<undefined> = source.pipe(Effect.as(undefined))
+// @ts-expect-error Effect.asVoid widens the success type to void.
+const voidSuccess: Effect.Effect<undefined> = source.pipe(Effect.asVoid)
+
+test("Effect.as preserves the exact undefined success type", () => {
+  expect(Effect.runSync(exactUndefined)).toBeUndefined()
+  expect(Effect.runSync(voidSuccess)).toBeUndefined()
+})

packages/desktop/src/main/files/apps.ts

@@ -28,7 +28,7 @@ const checkMacosApp = Effect.fn("DesktopFiles.checkMacosApp")(function* (appName
 
   return yield* Effect.tryPromise(() => execFilePromise("which", [appName])).pipe(
     Effect.as(true),
-    Effect.catch(() => Effect.succeed(false)),
+    Effect.orElseSucceed(() => false),
   )
 })
 
@@ -36,7 +36,7 @@ const resolveWindowsAppPath = Effect.fn("DesktopFiles.resolveWindowsAppPath")(fu
   const fs = yield* FileSystem.FileSystem
   const path = yield* Path.Path
   const result = yield* Effect.tryPromise(() => execFilePromise("where", [appName])).pipe(
-    Effect.catch(() => Effect.succeed(undefined)),
+    Effect.orElseSucceed(() => undefined),
   )
   if (!result) return null
 
@@ -110,7 +110,7 @@ const resolveWindowsAppPath = Effect.fn("DesktopFiles.resolveWindowsAppPath")(fu
     for (const file of paths) {
       const dirs = [path.dirname(file), path.dirname(path.dirname(file)), path.dirname(path.dirname(path.dirname(file)))]
       for (const dir of dirs) {
-        const entries = yield* fs.readDirectory(dir).pipe(Effect.catch(() => Effect.succeed([])))
+        const entries = yield* fs.readDirectory(dir).pipe(Effect.orElseSucceed(() => []))
         for (const entry of entries) {
           const candidate = path.join(dir, entry)
           if (!hasExt(candidate, "exe")) continue
@@ -130,8 +130,5 @@ const resolveWindowsAppPath = Effect.fn("DesktopFiles.resolveWindowsAppPath")(fu
 })
 
 function exists(fs: FileSystem.FileSystem, path: string) {
-  return fs.access(path).pipe(
-    Effect.as(true),
-    Effect.catch(() => Effect.succeed(false)),
-  )
+  return fs.exists(path).pipe(Effect.orElseSucceed(() => false))
 }

packages/desktop/src/main/files/index.ts

@@ -85,10 +85,7 @@ function make(fs: FileSystem.FileSystem, path: Path.Path) {
       )
     }),
     revealPath: Effect.fn("DesktopFiles.revealPath")(function* (target: string) {
-      const exists = yield* fs.stat(target).pipe(
-        Effect.as(true),
-        Effect.catch(() => Effect.succeed(false)),
-      )
+      const exists = yield* fs.exists(target).pipe(Effect.orElseSucceed(() => false))
       if (!exists) return false
       shell.showItemInFolder(target)
       return true

packages/desktop/src/main/native/logging.ts

@@ -163,7 +163,7 @@ export const tail = Effect.fn("DesktopLogging.tail")(function* () {
     const contents = yield* fs.readFileString(path)
     const lines = contents.split("\n")
     return lines.slice(Math.max(0, lines.length - TAIL_LINES)).join("\n")
-  }).pipe(Effect.catch(() => Effect.succeed("")))
+  }).pipe(Effect.orElseSucceed(() => ""))
 })
 
 function initRunDirectory(fs: FileSystem.FileSystem, path: Path.Path) {

packages/desktop/src/main/service/desktop-cli.ts

@@ -95,7 +95,7 @@ export const cleanStages = Effect.fn("DesktopCli.cleanStages")(function* (binary
     Effect.fnUntraced(function* (entry) {
       const target = path.join(root, entry)
       if (target === current) return
-      const stat = yield* fs.stat(target).pipe(Effect.catch(() => Effect.succeed(undefined)))
+      const stat = yield* fs.stat(target).pipe(Effect.orElseSucceed(() => undefined))
       if (stat?.type !== "Directory") return
       yield* fs
         .remove(target, { recursive: true, force: true })

packages/desktop/src/main/storage/cleanup.ts

@@ -19,7 +19,7 @@ export const cleanupStoreFiles = Effect.fn("Storage.cleanupStoreFiles")(function
 ) {
   const fs = yield* FileSystem.FileSystem
   const path = yield* Path.Path
-  const entries = yield* fs.readDirectory(userDataPath).pipe(Effect.catch(() => Effect.succeed([])))
+  const entries = yield* fs.readDirectory(userDataPath).pipe(Effect.orElseSucceed(() => []))
   const candidates = (yield* Effect.forEach(
     entries,
     Effect.fnUntraced(function* (entry) {
@@ -27,7 +27,7 @@ export const cleanupStoreFiles = Effect.fn("Storage.cleanupStoreFiles")(function
       if (!kind) return
 
       const file = path.join(userDataPath, entry)
-      const stats = yield* fs.stat(file).pipe(Effect.catch(() => Effect.succeed(undefined)))
+      const stats = yield* fs.stat(file).pipe(Effect.orElseSucceed(() => undefined))
       if (stats?.type !== "File") return
 
       return {
@@ -74,7 +74,7 @@ export const deleteStoreFileIfEmpty = Effect.fn("Storage.deleteStoreFileIfEmpty"
   const fs = yield* FileSystem.FileSystem
   const path = yield* Path.Path
   const file = path.join(userDataPath, name)
-  const stats = yield* fs.stat(file).pipe(Effect.catch(() => Effect.succeed(undefined)))
+  const stats = yield* fs.stat(file).pipe(Effect.orElseSucceed(() => undefined))
   if (stats?.type !== "File") return false
   if (!(yield* isEmptyStore(file, stats.size))) return false
 
@@ -91,7 +91,7 @@ const isEmptyStore = Effect.fn("Storage.isEmptyStore")(function* (file: string,
   if (size > FileSystem.Size(EMPTY_STORE_MAX_BYTES)) return false
 
   const fs = yield* FileSystem.FileSystem
-  const raw = yield* fs.readFileString(file).pipe(Effect.catch(() => Effect.succeed(undefined)))
+  const raw = yield* fs.readFileString(file).pipe(Effect.orElseSucceed(() => undefined))
   if (raw === undefined) return false
   if (raw.trim() === "") return true
 

packages/http-recorder/src/cassette/store.ts

@@ -98,12 +98,12 @@ export const fileSystem = (
       const pathFor = (name: string) => cassettePath(directory, name)
       const walk = (current: string): Effect.Effect<ReadonlyArray<string>> =>
         Effect.gen(function* () {
-          const entries = yield* fs.readDirectory(current).pipe(Effect.catch(() => Effect.succeed([] as string[])))
+          const entries = yield* fs.readDirectory(current).pipe(Effect.orElseSucceed(() => [] as string[]))
           const nested = yield* Effect.forEach(entries, (entry) => {
             const full = path.join(current, entry)
             return fs.stat(full).pipe(
               Effect.flatMap((stat) => (stat.type === "Directory" ? walk(full) : Effect.succeed([full]))),
-              Effect.catch(() => Effect.succeed([] as string[])),
+              Effect.orElseSucceed(() => [] as string[]),
             )
           })
           return nested.flat()
@@ -144,11 +144,7 @@ export const fileSystem = (
               recorded.set(name, { interactions, findings: interactionFindings })
             }),
           ),
-        exists: (name) =>
-          fs.access(pathFor(name)).pipe(
-            Effect.as(true),
-            Effect.catch(() => Effect.succeed(false)),
-          ),
+        exists: (name) => fs.exists(pathFor(name)).pipe(Effect.orElseSucceed(() => false)),
         list: () =>
           walk(directory).pipe(
             Effect.map((files) =>

packages/util/src/fs-util.ts

@@ -188,7 +188,7 @@ export namespace FSUtil {
         let current = start
         while (true) {
           const matches = yield* scan(pattern, { cwd: current, absolute: true, include: "file", dot: true }).pipe(
-            Effect.catch(() => Effect.succeed([] as string[])),
+            Effect.orElseSucceed(() => [] as string[]),
           )
           result.push(...matches)
           if (stop === current) break

packages/util/src/npm.ts

@@ -167,7 +167,7 @@ const layer = Layer.effect(
       const binDir = path.join(dir, "node_modules", ".bin")
 
       const pick = Effect.fnUntraced(function* () {
-        const files = yield* fs.readDirectory(binDir).pipe(Effect.catch(() => Effect.succeed([] as string[])))
+        const files = yield* fs.readDirectory(binDir).pipe(Effect.orElseSucceed(() => [] as string[]))
 
         if (files.length === 0) return Option.none<string>()
         // Caller picked a specific bin (e.g. pyright exposes both `pyright` and

script/ast-grep/effect-simplifications/README.md

@@ -0,0 +1,17 @@
+# Effect simplification rules
+
+The dedicated config scans both TypeScript and TSX with equivalent rules. The
+generic ast-grep config intentionally does not load these rules.
+
+Ignored callback parameters are supported only when they are simple ASCII
+underscore-prefixed identifiers such as `_`, `_error`, or `_value`, optionally
+with a type annotation. A rule reports the callback only when the exact target
+subtree contains no underscore-prefixed identifier-like node, proving the
+binding is unused without relying on unavailable TypeScript scope resolution.
+
+This proof is intentionally conservative. Destructured, defaulted, rest,
+optional, non-underscore, and Unicode parameters are excluded. A nested binding
+or property whose name starts with `_` also suppresses the diagnostic, even when
+it does not reference the callback parameter. Regular-function callbacks are
+excluded when their target captures `this`, `arguments`, or a meta-property such
+as `new.target` or `import.meta`.

script/ast-grep/effect-simplifications/rule-tests/__snapshots__/no-effect-and-then-succeed-undefined-snapshot.yml

@@ -0,0 +1,28 @@
+id: no-effect-and-then-succeed-undefined
+snapshots:
+  Effect.andThen(effect, Effect.succeed(undefined)):
+    labels:
+      - source: Effect.andThen(effect, Effect.succeed(undefined))
+        style: primary
+        start: 0
+        end: 49
+  ? |
+    effect.pipe(
+      Effect.andThen(
+        Effect.succeed(undefined),
+      ),
+    )
+  : labels:
+      - source: |-
+          Effect.andThen(
+              Effect.succeed(undefined),
+            )
+        style: primary
+        start: 15
+        end: 65
+  effect.pipe(Effect.andThen(Effect.succeed(undefined))):
+    labels:
+      - source: Effect.andThen(Effect.succeed(undefined))
+        style: primary
+        start: 12
+        end: 53

script/ast-grep/effect-simplifications/rule-tests/__snapshots__/no-effect-and-then-succeed-undefined-tsx-snapshot.yml

@@ -0,0 +1,32 @@
+id: no-effect-and-then-succeed-undefined-tsx
+snapshots:
+  ? |
+    const view = (
+      <Widget
+        value={effect.pipe(
+          Effect.andThen(
+            Effect.succeed(undefined),
+          ),
+        )}
+      />
+    )
+  : labels:
+      - source: |-
+          Effect.andThen(
+                  Effect.succeed(undefined),
+                )
+        style: primary
+        start: 55
+        end: 113
+  const view = <Widget value={Effect.andThen(effect, Effect.succeed(undefined))} />:
+    labels:
+      - source: Effect.andThen(effect, Effect.succeed(undefined))
+        style: primary
+        start: 28
+        end: 77
+  const view = <Widget value={effect.pipe(Effect.andThen(Effect.succeed(undefined)))} />:
+    labels:
+      - source: Effect.andThen(Effect.succeed(undefined))
+        style: primary
+        start: 40
+        end: 81

script/ast-grep/effect-simplifications/rule-tests/__snapshots__/no-effect-catch-succeed-snapshot.yml

@@ -0,0 +1,95 @@
+id: no-effect-catch-succeed
+snapshots:
+  'Effect.catch(effect, () => Effect.succeed({ reason: "fallback" }))':
+    labels:
+      - source: 'Effect.catch(effect, () => Effect.succeed({ reason: "fallback" }))'
+        style: primary
+        start: 0
+        end: 66
+  ? |
+    effect.pipe(
+      Effect.catch(() => Effect.succeed([] as string[])),
+    )
+  : labels:
+      - source: Effect.catch(() => Effect.succeed([] as string[]))
+        style: primary
+        start: 15
+        end: 65
+  effect.pipe(Effect.catch(() => Effect.succeed(fallback))):
+    labels:
+      - source: Effect.catch(() => Effect.succeed(fallback))
+        style: primary
+        start: 12
+        end: 56
+  effect.pipe(Effect.catch(() => { return Effect.succeed(fallback) })):
+    labels:
+      - source: Effect.catch(() => { return Effect.succeed(fallback) })
+        style: primary
+        start: 12
+        end: 67
+  effect.pipe(Effect.catch((_) => Effect.succeed(fallback))):
+    labels:
+      - source: Effect.catch((_) => Effect.succeed(fallback))
+        style: primary
+        start: 12
+        end: 57
+  "effect.pipe(Effect.catch((_cause: Cause) => Effect.succeed(fallback)))":
+    labels:
+      - source: "Effect.catch((_cause: Cause) => Effect.succeed(fallback))"
+        style: primary
+        start: 12
+        end: 69
+  effect.pipe(Effect.catch((_error) => Effect.succeed(fallback))):
+    labels:
+      - source: Effect.catch((_error) => Effect.succeed(fallback))
+        style: primary
+        start: 12
+        end: 62
+  "effect.pipe(Effect.catch((_error: Error) => { return Effect.succeed(fallback) }))":
+    labels:
+      - source: "Effect.catch((_error: Error) => { return Effect.succeed(fallback) })"
+        style: primary
+        start: 12
+        end: 80
+  effect.pipe(Effect.catch(_ => Effect.succeed(fallback))):
+    labels:
+      - source: Effect.catch(_ => Effect.succeed(fallback))
+        style: primary
+        start: 12
+        end: 55
+  effect.pipe(Effect.catch(_ => { return Effect.succeed(fallback) })):
+    labels:
+      - source: Effect.catch(_ => { return Effect.succeed(fallback) })
+        style: primary
+        start: 12
+        end: 66
+  effect.pipe(Effect.catch(_error => { return Effect.succeed(fallback) })):
+    labels:
+      - source: Effect.catch(_error => { return Effect.succeed(fallback) })
+        style: primary
+        start: 12
+        end: 71
+  effect.pipe(Effect.catch(function () { return Effect.succeed(fallback) })):
+    labels:
+      - source: Effect.catch(function () { return Effect.succeed(fallback) })
+        style: primary
+        start: 12
+        end: 73
+  effect.pipe(Effect.catch(function (_) { return Effect.succeed(fallback) })):
+    labels:
+      - source: Effect.catch(function (_) { return Effect.succeed(fallback) })
+        style: primary
+        start: 12
+        end: 74
+  effect.pipe(Effect.catch(function (_error) { return Effect.succeed(fallback) })):
+    labels:
+      - source: Effect.catch(function (_error) { return Effect.succeed(fallback) })
+        style: primary
+        start: 12
+        end: 79
+  "effect.pipe(Effect.catch(function (_error: Error) { return Effect.succeed(fallback) }))":
+    labels:
+      - source: "Effect.catch(function (_error: Error) { return Effect.succeed(fallback) })"
+        style: primary
+        start: 12
+        end: 86

script/ast-grep/effect-simplifications/rule-tests/__snapshots__/no-effect-catch-succeed-tsx-snapshot.yml

@@ -0,0 +1,38 @@
+id: no-effect-catch-succeed-tsx
+snapshots:
+  const view = <Widget value={Effect.catch(effect, () => Effect.succeed(fallback))} />:
+    labels:
+      - source: Effect.catch(effect, () => Effect.succeed(fallback))
+        style: primary
+        start: 28
+        end: 80
+  const view = <Widget value={effect.pipe(Effect.catch(() => Effect.succeed(fallback)))} />:
+    labels:
+      - source: Effect.catch(() => Effect.succeed(fallback))
+        style: primary
+        start: 40
+        end: 84
+  const view = <Widget value={effect.pipe(Effect.catch((_error) => Effect.succeed(fallback)))} />:
+    labels:
+      - source: Effect.catch((_error) => Effect.succeed(fallback))
+        style: primary
+        start: 40
+        end: 90
+  "const view = <Widget value={effect.pipe(Effect.catch((_error: Error) => Effect.succeed(fallback)))} />":
+    labels:
+      - source: "Effect.catch((_error: Error) => Effect.succeed(fallback))"
+        style: primary
+        start: 40
+        end: 97
+  const view = <Widget value={effect.pipe(Effect.catch(_error => { return Effect.succeed(fallback) }))} />:
+    labels:
+      - source: Effect.catch(_error => { return Effect.succeed(fallback) })
+        style: primary
+        start: 40
+        end: 99
+  const view = <Widget value={effect.pipe(Effect.catch(function (_error) { return Effect.succeed(fallback) }))} />:
+    labels:
+      - source: Effect.catch(function (_error) { return Effect.succeed(fallback) })
+        style: primary
+        start: 40
+        end: 107

script/ast-grep/effect-simplifications/rule-tests/__snapshots__/no-effect-flat-map-suspend-snapshot.yml

@@ -0,0 +1,100 @@
+id: no-effect-flat-map-suspend
+snapshots:
+  Effect.flatMap(effect, () => Effect.suspend(() => next)):
+    labels:
+      - source: Effect.flatMap(effect, () => Effect.suspend(() => next))
+        style: primary
+        start: 0
+        end: 56
+  ? |
+    effect.pipe(
+      Effect.flatMap(() =>
+        Effect.suspend(() => next),
+      ),
+    )
+  : labels:
+      - source: |-
+          Effect.flatMap(() =>
+              Effect.suspend(() => next),
+            )
+        style: primary
+        start: 15
+        end: 71
+  effect.pipe(Effect.flatMap(() => Effect.suspend(() => next))):
+    labels:
+      - source: Effect.flatMap(() => Effect.suspend(() => next))
+        style: primary
+        start: 12
+        end: 60
+  effect.pipe(Effect.flatMap(() => { return Effect.suspend(() => next) })):
+    labels:
+      - source: Effect.flatMap(() => { return Effect.suspend(() => next) })
+        style: primary
+        start: 12
+        end: 71
+  effect.pipe(Effect.flatMap((_) => Effect.suspend(() => next))):
+    labels:
+      - source: Effect.flatMap((_) => Effect.suspend(() => next))
+        style: primary
+        start: 12
+        end: 61
+  effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => next))):
+    labels:
+      - source: Effect.flatMap((_value) => Effect.suspend(() => next))
+        style: primary
+        start: 12
+        end: 66
+  "effect.pipe(Effect.flatMap((_value: Value) => Effect.suspend(() => next)))":
+    labels:
+      - source: "Effect.flatMap((_value: Value) => Effect.suspend(() => next))"
+        style: primary
+        start: 12
+        end: 73
+  "effect.pipe(Effect.flatMap((_value: Value) => { return Effect.suspend(() => next) }))":
+    labels:
+      - source: "Effect.flatMap((_value: Value) => { return Effect.suspend(() => next) })"
+        style: primary
+        start: 12
+        end: 84
+  effect.pipe(Effect.flatMap(_ => Effect.suspend(() => next))):
+    labels:
+      - source: Effect.flatMap(_ => Effect.suspend(() => next))
+        style: primary
+        start: 12
+        end: 59
+  effect.pipe(Effect.flatMap(_ => { return Effect.suspend(() => next) })):
+    labels:
+      - source: Effect.flatMap(_ => { return Effect.suspend(() => next) })
+        style: primary
+        start: 12
+        end: 70
+  effect.pipe(Effect.flatMap(_value => { return Effect.suspend(() => next) })):
+    labels:
+      - source: Effect.flatMap(_value => { return Effect.suspend(() => next) })
+        style: primary
+        start: 12
+        end: 75
+  effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => next) })):
+    labels:
+      - source: Effect.flatMap(function () { return Effect.suspend(() => next) })
+        style: primary
+        start: 12
+        end: 77
+  effect.pipe(Effect.flatMap(function (_) { return Effect.suspend(() => next) })):
+    labels:
+      - source: Effect.flatMap(function (_) { return Effect.suspend(() => next) })
+        style: primary
+        start: 12
+        end: 78
+  effect.pipe(Effect.flatMap(function (_value) { return Effect.suspend(() => next) })):
+    labels:
+      - source: Effect.flatMap(function (_value) { return Effect.suspend(() => next) })
+        style: primary
+        start: 12
+        end: 83
+  "effect.pipe(Effect.flatMap(function (_value: Value) { return Effect.suspend(() => next) }))":
+    labels:
+      - source: "Effect.flatMap(function (_value: Value) { return Effect.suspend(() => next) })"
+        style: primary
+        start: 12
+        end: 90

script/ast-grep/effect-simplifications/rule-tests/__snapshots__/no-effect-flat-map-suspend-tsx-snapshot.yml

@@ -0,0 +1,38 @@
+id: no-effect-flat-map-suspend-tsx
+snapshots:
+  const view = <Widget value={Effect.flatMap(effect, () => Effect.suspend(() => next))} />:
+    labels:
+      - source: Effect.flatMap(effect, () => Effect.suspend(() => next))
+        style: primary
+        start: 28
+        end: 84
+  const view = <Widget value={effect.pipe(Effect.flatMap(() => Effect.suspend(() => next)))} />:
+    labels:
+      - source: Effect.flatMap(() => Effect.suspend(() => next))
+        style: primary
+        start: 40
+        end: 88
+  const view = <Widget value={effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => next)))} />:
+    labels:
+      - source: Effect.flatMap((_value) => Effect.suspend(() => next))
+        style: primary
+        start: 40
+        end: 94
+  "const view = <Widget value={effect.pipe(Effect.flatMap((_value: Value) => Effect.suspend(() => next)))} />":
+    labels:
+      - source: "Effect.flatMap((_value: Value) => Effect.suspend(() => next))"
+        style: primary
+        start: 40
+        end: 101
+  const view = <Widget value={effect.pipe(Effect.flatMap(_value => { return Effect.suspend(() => next) }))} />:
+    labels:
+      - source: Effect.flatMap(_value => { return Effect.suspend(() => next) })
+        style: primary
+        start: 40
+        end: 103
+  const view = <Widget value={effect.pipe(Effect.flatMap(function (_value) { return Effect.suspend(() => next) }))} />:
+    labels:
+      - source: Effect.flatMap(function (_value) { return Effect.suspend(() => next) })
+        style: primary
+        start: 40
+        end: 111

script/ast-grep/effect-simplifications/rule-tests/no-effect-and-then-succeed-undefined-test.yml

@@ -0,0 +1,21 @@
+id: no-effect-and-then-succeed-undefined
+valid:
+  - effect.pipe(Effect.as(undefined))
+  - Effect.as(effect, undefined)
+  - effect.pipe(Effect.asVoid)
+  - effect.pipe(Effect.andThen(Effect.succeed(null)))
+  - effect.pipe(Effect.andThen(() => Effect.succeed(undefined)))
+  - effect.pipe(Effect.andThen(Effect.sync(() => undefined)))
+  - effect.pipe(Stream.andThen(Effect.succeed(undefined)))
+  - Effect.andThen(effect, options, Effect.succeed(undefined))
+  - Effect.andThen(first, second, third, Effect.succeed(undefined))
+  - Effect.succeed(undefined)
+invalid:
+  - effect.pipe(Effect.andThen(Effect.succeed(undefined)))
+  - Effect.andThen(effect, Effect.succeed(undefined))
+  - |
+    effect.pipe(
+      Effect.andThen(
+        Effect.succeed(undefined),
+      ),
+    )

script/ast-grep/effect-simplifications/rule-tests/no-effect-and-then-succeed-undefined-tsx-test.yml

@@ -0,0 +1,21 @@
+id: no-effect-and-then-succeed-undefined-tsx
+valid:
+  - const view = <Widget value={effect.pipe(Effect.as(undefined))} />
+  - const view = <Widget value={Effect.as(effect, undefined)} />
+  - const view = <Widget value={effect.pipe(Effect.asVoid)} />
+  - const view = <Widget value={effect.pipe(Effect.andThen(Effect.succeed(null)))} />
+  - const view = <Widget value={Effect.andThen(effect, options, Effect.succeed(undefined))} />
+  - const view = <Widget value={Stream.andThen(effect, Effect.succeed(undefined))} />
+invalid:
+  - const view = <Widget value={effect.pipe(Effect.andThen(Effect.succeed(undefined)))} />
+  - const view = <Widget value={Effect.andThen(effect, Effect.succeed(undefined))} />
+  - |
+    const view = (
+      <Widget
+        value={effect.pipe(
+          Effect.andThen(
+            Effect.succeed(undefined),
+          ),
+        )}
+      />
+    )

script/ast-grep/effect-simplifications/rule-tests/no-effect-catch-succeed-test.yml

@@ -0,0 +1,49 @@
+id: no-effect-catch-succeed
+valid:
+  - effect.pipe(Effect.orElseSucceed(() => fallback))
+  - Effect.orElseSucceed(effect, () => fallback)
+  - effect.pipe(Effect.catch((error) => Effect.succeed(error)))
+  - effect.pipe(Effect.catch((error) => Effect.succeed(fallback)))
+  - effect.pipe(Effect.catch((_) => Effect.succeed(_)))
+  - effect.pipe(Effect.catch((_) => Effect.succeed(use(_))))
+  - effect.pipe(Effect.catch((_) => { return Effect.succeed(_) }))
+  - effect.pipe(Effect.catch((_error) => Effect.succeed(_error)))
+  - effect.pipe(Effect.catch((_error) => Effect.succeed({ _error })))
+  - "effect.pipe(Effect.catch((_error: Error) => Effect.succeed(use(_error))))"
+  - effect.pipe(Effect.catch((_error) => Effect.succeed(values.map((_error) => _error))))
+  - effect.pipe(Effect.catch(({ message }) => Effect.succeed(fallback)))
+  - effect.pipe(Effect.catch((_error = fallbackError) => Effect.succeed(fallback)))
+  - effect.pipe(Effect.catch((..._errors) => Effect.succeed(fallback)))
+  - "effect.pipe(Effect.catch((_error?: Error) => Effect.succeed(fallback)))"
+  - effect.pipe(Effect.catch(() => Effect.void))
+  - effect.pipe(Effect.catch(() => Effect.sync(fallback)))
+  - effect.pipe(Other.catch(() => Effect.succeed(fallback)))
+  - Effect.catch(effect, options, () => Effect.succeed(fallback))
+  - Effect.catch(first, second, third, () => Effect.succeed(fallback))
+  - effect.pipe(Effect.catch(() => { log(); return Effect.succeed(fallback) }))
+  - effect.pipe(Effect.catch(function () { return Effect.succeed(this.fallback) }))
+  - effect.pipe(Effect.catch(function () { return Effect.succeed(arguments[0]) }))
+  - effect.pipe(Effect.catch(function () { return Effect.succeed(new.target) }))
+  - effect.pipe(Effect.catch(function () { return Effect.succeed(import.meta) }))
+  - effect.pipe(Effect.catch(function (_) { return Effect.succeed(_) }))
+  - "effect.pipe(Effect.catch(function (_error: Error) { return Effect.succeed(_error) }))"
+  - effect.pipe(Effect.catch(function (_error) { return Effect.succeed(new.target) }))
+invalid:
+  - effect.pipe(Effect.catch(() => Effect.succeed(fallback)))
+  - 'Effect.catch(effect, () => Effect.succeed({ reason: "fallback" }))'
+  - effect.pipe(Effect.catch((_) => Effect.succeed(fallback)))
+  - effect.pipe(Effect.catch(_ => Effect.succeed(fallback)))
+  - effect.pipe(Effect.catch(_ => { return Effect.succeed(fallback) }))
+  - effect.pipe(Effect.catch(() => { return Effect.succeed(fallback) }))
+  - effect.pipe(Effect.catch(function () { return Effect.succeed(fallback) }))
+  - effect.pipe(Effect.catch(function (_) { return Effect.succeed(fallback) }))
+  - effect.pipe(Effect.catch((_error) => Effect.succeed(fallback)))
+  - effect.pipe(Effect.catch(_error => { return Effect.succeed(fallback) }))
+  - "effect.pipe(Effect.catch((_cause: Cause) => Effect.succeed(fallback)))"
+  - "effect.pipe(Effect.catch((_error: Error) => { return Effect.succeed(fallback) }))"
+  - effect.pipe(Effect.catch(function (_error) { return Effect.succeed(fallback) }))
+  - "effect.pipe(Effect.catch(function (_error: Error) { return Effect.succeed(fallback) }))"
+  - |
+    effect.pipe(
+      Effect.catch(() => Effect.succeed([] as string[])),
+    )

script/ast-grep/effect-simplifications/rule-tests/no-effect-catch-succeed-tsx-test.yml

@@ -0,0 +1,21 @@
+id: no-effect-catch-succeed-tsx
+valid:
+  - const view = <Widget value={effect.pipe(Effect.orElseSucceed(() => fallback))} />
+  - const view = <Widget value={effect.pipe(Effect.catch((error) => Effect.succeed(error)))} />
+  - const view = <Widget value={effect.pipe(Effect.catch((error) => Effect.succeed(fallback)))} />
+  - const view = <Widget value={effect.pipe(Effect.catch((_error) => Effect.succeed(_error)))} />
+  - const view = <Widget value={effect.pipe(Effect.catch((_error) => Effect.succeed({ _error })))} />
+  - "const view = <Widget value={effect.pipe(Effect.catch((_error: Error) => Effect.succeed(use(_error))))} />"
+  - const view = <Widget value={effect.pipe(Effect.catch((_error) => Effect.succeed(values.map((_error) => _error))))} />
+  - const view = <Widget value={effect.pipe(Effect.catch(({ message }) => Effect.succeed(fallback)))} />
+  - const view = <Widget value={Effect.catch(effect, options, () => Effect.succeed(fallback))} />
+  - const view = <Widget value={effect.pipe(Effect.catch(() => { log(); return Effect.succeed(fallback) }))} />
+  - const view = <Widget value={effect.pipe(Effect.catch(function () { return Effect.succeed(new.target) }))} />
+  - const view = <Widget value={effect.pipe(Effect.catch(function () { return Effect.succeed(import.meta) }))} />
+invalid:
+  - const view = <Widget value={effect.pipe(Effect.catch(() => Effect.succeed(fallback)))} />
+  - const view = <Widget value={Effect.catch(effect, () => Effect.succeed(fallback))} />
+  - const view = <Widget value={effect.pipe(Effect.catch((_error) => Effect.succeed(fallback)))} />
+  - const view = <Widget value={effect.pipe(Effect.catch(_error => { return Effect.succeed(fallback) }))} />
+  - "const view = <Widget value={effect.pipe(Effect.catch((_error: Error) => Effect.succeed(fallback)))} />"
+  - const view = <Widget value={effect.pipe(Effect.catch(function (_error) { return Effect.succeed(fallback) }))} />

script/ast-grep/effect-simplifications/rule-tests/no-effect-flat-map-suspend-test.yml

@@ -0,0 +1,52 @@
+id: no-effect-flat-map-suspend
+valid:
+  - effect.pipe(Effect.andThen(Effect.suspend(() => next)))
+  - Effect.andThen(effect, Effect.suspend(() => next))
+  - effect.pipe(Effect.flatMap((value) => Effect.suspend(() => use(value))))
+  - effect.pipe(Effect.flatMap((value) => Effect.suspend(() => next)))
+  - effect.pipe(Effect.flatMap((_) => Effect.suspend(() => use(_))))
+  - effect.pipe(Effect.flatMap((_) => { return Effect.suspend(() => use(_)) }))
+  - effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => use(_value))))
+  - effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => ({ _value }))))
+  - "effect.pipe(Effect.flatMap((_value: Value) => Effect.suspend(() => use(_value))))"
+  - effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => values.map((_value) => use(_value)))))
+  - effect.pipe(Effect.flatMap(({ value }) => Effect.suspend(() => next)))
+  - effect.pipe(Effect.flatMap((_value = fallback) => Effect.suspend(() => next)))
+  - effect.pipe(Effect.flatMap((..._values) => Effect.suspend(() => next)))
+  - "effect.pipe(Effect.flatMap((_value?: Value) => Effect.suspend(() => next)))"
+  - effect.pipe(Effect.flatMap(() => Effect.suspend(thunk)))
+  - effect.pipe(Effect.flatMap(() => Effect.suspend(getThunk())))
+  - effect.pipe(Effect.flatMap(() => Effect.suspend(function thunk() { return next })))
+  - effect.pipe(Effect.flatMap(() => Effect.sync(thunk)))
+  - effect.pipe(Stream.flatMap(() => Effect.suspend(() => next)))
+  - Effect.flatMap(effect, options, () => Effect.suspend(() => next))
+  - Effect.flatMap(first, second, third, () => Effect.suspend(() => next))
+  - effect.pipe(Effect.flatMap(() => { log(); return Effect.suspend(() => next) }))
+  - effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => this.next) }))
+  - effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => arguments[0]) }))
+  - effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => new.target) }))
+  - effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => import.meta) }))
+  - effect.pipe(Effect.flatMap(function (_) { return Effect.suspend(() => use(_)) }))
+  - "effect.pipe(Effect.flatMap(function (_value: Value) { return Effect.suspend(() => use(_value)) }))"
+  - effect.pipe(Effect.flatMap(function (_value) { return Effect.suspend(() => new.target) }))
+invalid:
+  - effect.pipe(Effect.flatMap(() => Effect.suspend(() => next)))
+  - Effect.flatMap(effect, () => Effect.suspend(() => next))
+  - effect.pipe(Effect.flatMap((_) => Effect.suspend(() => next)))
+  - effect.pipe(Effect.flatMap(_ => Effect.suspend(() => next)))
+  - effect.pipe(Effect.flatMap(_ => { return Effect.suspend(() => next) }))
+  - effect.pipe(Effect.flatMap(() => { return Effect.suspend(() => next) }))
+  - effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => next) }))
+  - effect.pipe(Effect.flatMap(function (_) { return Effect.suspend(() => next) }))
+  - effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => next)))
+  - effect.pipe(Effect.flatMap(_value => { return Effect.suspend(() => next) }))
+  - "effect.pipe(Effect.flatMap((_value: Value) => Effect.suspend(() => next)))"
+  - "effect.pipe(Effect.flatMap((_value: Value) => { return Effect.suspend(() => next) }))"
+  - effect.pipe(Effect.flatMap(function (_value) { return Effect.suspend(() => next) }))
+  - "effect.pipe(Effect.flatMap(function (_value: Value) { return Effect.suspend(() => next) }))"
+  - |
+    effect.pipe(
+      Effect.flatMap(() =>
+        Effect.suspend(() => next),
+      ),
+    )

script/ast-grep/effect-simplifications/rule-tests/no-effect-flat-map-suspend-tsx-test.yml

@@ -0,0 +1,21 @@
+id: no-effect-flat-map-suspend-tsx
+valid:
+  - const view = <Widget value={effect.pipe(Effect.andThen(Effect.suspend(() => next)))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap((value) => Effect.suspend(() => use(value))))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap((value) => Effect.suspend(() => next)))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => use(_value))))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => ({ _value }))))} />
+  - "const view = <Widget value={effect.pipe(Effect.flatMap((_value: Value) => Effect.suspend(() => use(_value))))} />"
+  - const view = <Widget value={effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => values.map((_value) => use(_value)))))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap(({ value }) => Effect.suspend(() => next)))} />
+  - const view = <Widget value={Effect.flatMap(effect, options, () => Effect.suspend(() => next))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap(() => Effect.suspend(thunk)))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => new.target) }))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap(function () { return Effect.suspend(() => import.meta) }))} />
+invalid:
+  - const view = <Widget value={effect.pipe(Effect.flatMap(() => Effect.suspend(() => next)))} />
+  - const view = <Widget value={Effect.flatMap(effect, () => Effect.suspend(() => next))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap((_value) => Effect.suspend(() => next)))} />
+  - const view = <Widget value={effect.pipe(Effect.flatMap(_value => { return Effect.suspend(() => next) }))} />
+  - "const view = <Widget value={effect.pipe(Effect.flatMap((_value: Value) => Effect.suspend(() => next)))} />"
+  - const view = <Widget value={effect.pipe(Effect.flatMap(function (_value) { return Effect.suspend(() => next) }))} />

script/ast-grep/effect-simplifications/rules/no-effect-and-then-succeed-undefined-tsx.yml

@@ -0,0 +1,9 @@
+id: no-effect-and-then-succeed-undefined-tsx
+language: Tsx
+message: Use Effect.as(undefined) to preserve the exact undefined success type.
+severity: error
+rule:
+  all:
+    - pattern: Effect.andThen($$$SELF, Effect.succeed(undefined))
+    - not:
+        pattern: Effect.andThen($_FIRST, $_SECOND, $$$REST)

script/ast-grep/effect-simplifications/rules/no-effect-and-then-succeed-undefined.yml

@@ -0,0 +1,9 @@
+id: no-effect-and-then-succeed-undefined
+language: TypeScript
+message: Use Effect.as(undefined) to preserve the exact undefined success type.
+severity: error
+rule:
+  all:
+    - pattern: Effect.andThen($$$SELF, Effect.succeed(undefined))
+    - not:
+        pattern: Effect.andThen($_FIRST, $_SECOND, $$$REST)

script/ast-grep/effect-simplifications/rules/no-effect-catch-succeed-tsx.yml

@@ -0,0 +1,61 @@
+id: no-effect-catch-succeed-tsx
+language: Tsx
+message: Use Effect.orElseSucceed for constant failure recovery.
+severity: error
+rule:
+  all:
+    - any:
+        - pattern: Effect.catch($$$SELF, () => Effect.succeed($VALUE))
+        - pattern: Effect.catch($$$SELF, () => { return Effect.succeed($VALUE) })
+        - pattern: Effect.catch($$$SELF, ($IGNORED) => Effect.succeed($IGNORED_VALUE))
+        - pattern: Effect.catch($$$SELF, ($IGNORED) => { return Effect.succeed($IGNORED_VALUE) })
+        - pattern: Effect.catch($$$SELF, $IGNORED => Effect.succeed($IGNORED_VALUE))
+        - pattern: Effect.catch($$$SELF, $IGNORED => { return Effect.succeed($IGNORED_VALUE) })
+        - pattern: "Effect.catch($$$SELF, ($IGNORED: $_TYPE) => Effect.succeed($IGNORED_VALUE))"
+        - pattern: "Effect.catch($$$SELF, ($IGNORED: $_TYPE) => { return Effect.succeed($IGNORED_VALUE) })"
+        - pattern: Effect.catch($$$SELF, function () { return Effect.succeed($FUNCTION_VALUE) })
+        - pattern: Effect.catch($$$SELF, function ($FUNCTION_IGNORED) { return Effect.succeed($FUNCTION_IGNORED_VALUE) })
+        - pattern: "Effect.catch($$$SELF, function ($FUNCTION_IGNORED: $_TYPE) { return Effect.succeed($FUNCTION_IGNORED_VALUE) })"
+    - not:
+        pattern: Effect.catch($_FIRST, $_SECOND, $$$REST)
+constraints:
+  IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  IGNORED_VALUE:
+    all:
+      - not:
+          regex: ^_[A-Za-z0-9_$]*$
+      - not:
+          has:
+            regex: ^_[A-Za-z0-9_$]*$
+            stopBy: end
+  FUNCTION_VALUE:
+    all:
+      - not:
+          any:
+            - regex: ^arguments$
+            - kind: this
+            - kind: meta_property
+      - not:
+          has:
+            any:
+              - regex: ^arguments$
+              - kind: this
+              - kind: meta_property
+            stopBy: end
+  FUNCTION_IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  FUNCTION_IGNORED_VALUE:
+    all:
+      - not:
+          any:
+            - regex: ^(_[A-Za-z0-9_$]*|arguments)$
+            - kind: this
+            - kind: meta_property
+      - not:
+          has:
+            any:
+              - regex: ^(_[A-Za-z0-9_$]*|arguments)$
+              - kind: this
+              - kind: meta_property
+            stopBy: end

script/ast-grep/effect-simplifications/rules/no-effect-catch-succeed.yml

@@ -0,0 +1,61 @@
+id: no-effect-catch-succeed
+language: TypeScript
+message: Use Effect.orElseSucceed for constant failure recovery.
+severity: error
+rule:
+  all:
+    - any:
+        - pattern: Effect.catch($$$SELF, () => Effect.succeed($VALUE))
+        - pattern: Effect.catch($$$SELF, () => { return Effect.succeed($VALUE) })
+        - pattern: Effect.catch($$$SELF, ($IGNORED) => Effect.succeed($IGNORED_VALUE))
+        - pattern: Effect.catch($$$SELF, ($IGNORED) => { return Effect.succeed($IGNORED_VALUE) })
+        - pattern: Effect.catch($$$SELF, $IGNORED => Effect.succeed($IGNORED_VALUE))
+        - pattern: Effect.catch($$$SELF, $IGNORED => { return Effect.succeed($IGNORED_VALUE) })
+        - pattern: "Effect.catch($$$SELF, ($IGNORED: $_TYPE) => Effect.succeed($IGNORED_VALUE))"
+        - pattern: "Effect.catch($$$SELF, ($IGNORED: $_TYPE) => { return Effect.succeed($IGNORED_VALUE) })"
+        - pattern: Effect.catch($$$SELF, function () { return Effect.succeed($FUNCTION_VALUE) })
+        - pattern: Effect.catch($$$SELF, function ($FUNCTION_IGNORED) { return Effect.succeed($FUNCTION_IGNORED_VALUE) })
+        - pattern: "Effect.catch($$$SELF, function ($FUNCTION_IGNORED: $_TYPE) { return Effect.succeed($FUNCTION_IGNORED_VALUE) })"
+    - not:
+        pattern: Effect.catch($_FIRST, $_SECOND, $$$REST)
+constraints:
+  IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  IGNORED_VALUE:
+    all:
+      - not:
+          regex: ^_[A-Za-z0-9_$]*$
+      - not:
+          has:
+            regex: ^_[A-Za-z0-9_$]*$
+            stopBy: end
+  FUNCTION_VALUE:
+    all:
+      - not:
+          any:
+            - regex: ^arguments$
+            - kind: this
+            - kind: meta_property
+      - not:
+          has:
+            any:
+              - regex: ^arguments$
+              - kind: this
+              - kind: meta_property
+            stopBy: end
+  FUNCTION_IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  FUNCTION_IGNORED_VALUE:
+    all:
+      - not:
+          any:
+            - regex: ^(_[A-Za-z0-9_$]*|arguments)$
+            - kind: this
+            - kind: meta_property
+      - not:
+          has:
+            any:
+              - regex: ^(_[A-Za-z0-9_$]*|arguments)$
+              - kind: this
+              - kind: meta_property
+            stopBy: end

script/ast-grep/effect-simplifications/rules/no-effect-flat-map-suspend-tsx.yml

@@ -0,0 +1,54 @@
+id: no-effect-flat-map-suspend-tsx
+language: Tsx
+message: Use effect-form Effect.andThen when the previous value is ignored.
+severity: error
+rule:
+  all:
+    - any:
+        - pattern: Effect.flatMap($$$SELF, () => Effect.suspend($THUNK))
+        - pattern: Effect.flatMap($$$SELF, () => { return Effect.suspend($THUNK) })
+        - pattern: Effect.flatMap($$$SELF, ($IGNORED) => Effect.suspend($IGNORED_THUNK))
+        - pattern: Effect.flatMap($$$SELF, ($IGNORED) => { return Effect.suspend($IGNORED_THUNK) })
+        - pattern: Effect.flatMap($$$SELF, $IGNORED => Effect.suspend($IGNORED_THUNK))
+        - pattern: Effect.flatMap($$$SELF, $IGNORED => { return Effect.suspend($IGNORED_THUNK) })
+        - pattern: "Effect.flatMap($$$SELF, ($IGNORED: $_TYPE) => Effect.suspend($IGNORED_THUNK))"
+        - pattern: "Effect.flatMap($$$SELF, ($IGNORED: $_TYPE) => { return Effect.suspend($IGNORED_THUNK) })"
+        - pattern: Effect.flatMap($$$SELF, function () { return Effect.suspend($FUNCTION_THUNK) })
+        - pattern: Effect.flatMap($$$SELF, function ($FUNCTION_IGNORED) { return Effect.suspend($FUNCTION_IGNORED_THUNK) })
+        - pattern: "Effect.flatMap($$$SELF, function ($FUNCTION_IGNORED: $_TYPE) { return Effect.suspend($FUNCTION_IGNORED_THUNK) })"
+    - not:
+        pattern: Effect.flatMap($_FIRST, $_SECOND, $$$REST)
+constraints:
+  THUNK:
+    kind: arrow_function
+  IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  IGNORED_THUNK:
+    all:
+      - kind: arrow_function
+      - not:
+          has:
+            regex: ^_[A-Za-z0-9_$]*$
+            stopBy: end
+  FUNCTION_THUNK:
+    all:
+      - kind: arrow_function
+      - not:
+          has:
+            any:
+              - regex: ^arguments$
+              - kind: this
+              - kind: meta_property
+            stopBy: end
+  FUNCTION_IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  FUNCTION_IGNORED_THUNK:
+    all:
+      - kind: arrow_function
+      - not:
+          has:
+            any:
+              - regex: ^(_[A-Za-z0-9_$]*|arguments)$
+              - kind: this
+              - kind: meta_property
+            stopBy: end

script/ast-grep/effect-simplifications/rules/no-effect-flat-map-suspend.yml

@@ -0,0 +1,54 @@
+id: no-effect-flat-map-suspend
+language: TypeScript
+message: Use effect-form Effect.andThen when the previous value is ignored.
+severity: error
+rule:
+  all:
+    - any:
+        - pattern: Effect.flatMap($$$SELF, () => Effect.suspend($THUNK))
+        - pattern: Effect.flatMap($$$SELF, () => { return Effect.suspend($THUNK) })
+        - pattern: Effect.flatMap($$$SELF, ($IGNORED) => Effect.suspend($IGNORED_THUNK))
+        - pattern: Effect.flatMap($$$SELF, ($IGNORED) => { return Effect.suspend($IGNORED_THUNK) })
+        - pattern: Effect.flatMap($$$SELF, $IGNORED => Effect.suspend($IGNORED_THUNK))
+        - pattern: Effect.flatMap($$$SELF, $IGNORED => { return Effect.suspend($IGNORED_THUNK) })
+        - pattern: "Effect.flatMap($$$SELF, ($IGNORED: $_TYPE) => Effect.suspend($IGNORED_THUNK))"
+        - pattern: "Effect.flatMap($$$SELF, ($IGNORED: $_TYPE) => { return Effect.suspend($IGNORED_THUNK) })"
+        - pattern: Effect.flatMap($$$SELF, function () { return Effect.suspend($FUNCTION_THUNK) })
+        - pattern: Effect.flatMap($$$SELF, function ($FUNCTION_IGNORED) { return Effect.suspend($FUNCTION_IGNORED_THUNK) })
+        - pattern: "Effect.flatMap($$$SELF, function ($FUNCTION_IGNORED: $_TYPE) { return Effect.suspend($FUNCTION_IGNORED_THUNK) })"
+    - not:
+        pattern: Effect.flatMap($_FIRST, $_SECOND, $$$REST)
+constraints:
+  THUNK:
+    kind: arrow_function
+  IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  IGNORED_THUNK:
+    all:
+      - kind: arrow_function
+      - not:
+          has:
+            regex: ^_[A-Za-z0-9_$]*$
+            stopBy: end
+  FUNCTION_THUNK:
+    all:
+      - kind: arrow_function
+      - not:
+          has:
+            any:
+              - regex: ^arguments$
+              - kind: this
+              - kind: meta_property
+            stopBy: end
+  FUNCTION_IGNORED:
+    regex: ^_[A-Za-z0-9_$]*(?:\s*:\s*.+)?$
+  FUNCTION_IGNORED_THUNK:
+    all:
+      - kind: arrow_function
+      - not:
+          has:
+            any:
+              - regex: ^(_[A-Za-z0-9_$]*|arguments)$
+              - kind: this
+              - kind: meta_property
+            stopBy: end

script/ast-grep/effect-simplifications/sgconfig.yml

@@ -0,0 +1,4 @@
+ruleDirs:
+  - rules
+testConfigs:
+  - testDir: rule-tests