feat(growth): decision log for learning (#3187)

Adds decision logging to track approved/edited/skipped Reddit growth candidates. The log feeds back into the Claude prompt to improve future candidate selection based on past patterns.

.claude/skills/setup-agent-team/growth-prompt.md

@@ -6,6 +6,14 @@ Your job: from the pre-fetched Reddit posts below, find the ONE best thread wher
 
 **IMPORTANT: Do NOT use any tools.** All data is provided below. Your entire response should be plain text output — no bash commands, no file reads, no tool calls. Just analyze the data and respond with your findings.
 
+## Past decisions
+
+The team has reviewed previous candidates. Learn from these patterns — what got approved, what got skipped, and how replies were edited. Prefer posts similar to approved ones and avoid patterns seen in skipped ones.
+
+```
+DECISIONS_PLACEHOLDER
+```
+
 ## Pre-fetched Reddit data
 
 The following posts were fetched automatically. Each post includes the title, selftext, subreddit, engagement stats, and the poster's recent comment history.

.claude/skills/setup-agent-team/growth.sh

@@ -82,10 +82,16 @@ fi
 # Inject Reddit data into prompt template
 REDDIT_JSON=$(cat "${REDDIT_DATA_FILE}")
 # Use bun for safe substitution to avoid sed escaping issues with JSON
+DECISIONS_FILE="${HOME}/.config/spawn/growth-decisions.md"
 bun -e "
+import { existsSync } from 'node:fs';
 const template = await Bun.file('${PROMPT_TEMPLATE}').text();
 const data = await Bun.file('${REDDIT_DATA_FILE}').text();
-const result = template.replace('REDDIT_DATA_PLACEHOLDER', data.trim());
+const decisionsPath = '${DECISIONS_FILE}';
+const decisions = existsSync(decisionsPath) ? await Bun.file(decisionsPath).text() : 'No past decisions yet.';
+const result = template
+  .replace('REDDIT_DATA_PLACEHOLDER', data.trim())
+  .replace('DECISIONS_PLACEHOLDER', decisions.trim());
 await Bun.write('${PROMPT_FILE}', result);
 "
 

.claude/skills/setup-spa/helpers.ts

@@ -5,7 +5,16 @@ import type { Result } from "@openrouter/spawn-shared";
 import type { Block } from "@slack/bolt";
 
 import { Database } from "bun:sqlite";
-import { existsSync, mkdirSync, readdirSync, readFileSync, rmSync, statSync, writeFileSync } from "node:fs";
+import {
+  appendFileSync,
+  existsSync,
+  mkdirSync,
+  readdirSync,
+  readFileSync,
+  rmSync,
+  statSync,
+  writeFileSync,
+} from "node:fs";
 import { dirname } from "node:path";
 import { Err, isString, Ok, toRecord } from "@openrouter/spawn-shared";
 import { slackifyMarkdown } from "slackify-markdown";
@@ -299,9 +308,10 @@ function rowToCandidate(r: RawCandidate): CandidateRow {
     draftReply: r.draft_reply,
     slackChannel: r.slack_channel ?? undefined,
     slackTs: r.slack_ts ?? undefined,
-    status: r.status === "approved" || r.status === "posted" || r.status === "skipped" || r.status === "error"
-      ? r.status
-      : "pending",
+    status:
+      r.status === "approved" || r.status === "posted" || r.status === "skipped" || r.status === "error"
+        ? r.status
+        : "pending",
     actionedBy: r.actioned_by ?? undefined,
     actionedAt: r.actioned_at ?? undefined,
     postedReply: r.posted_reply ?? undefined,
@@ -335,7 +345,12 @@ export function upsertCandidate(db: Database, candidate: CandidateRow): void {
 /** Look up a candidate by Reddit post ID. */
 export function findCandidate(db: Database, postId: string): CandidateRow | undefined {
   const row = db
-    .query<RawCandidate, [string]>("SELECT * FROM candidates WHERE post_id = ?")
+    .query<
+      RawCandidate,
+      [
+        string,
+      ]
+    >("SELECT * FROM candidates WHERE post_id = ?")
     .get(postId);
   return row ? rowToCandidate(row) : undefined;
 }
@@ -370,6 +385,43 @@ export function updateCandidateStatus(
   );
 }
 
+const DECISIONS_PATH = `${process.env.HOME ?? "/tmp"}/.config/spawn/growth-decisions.md`;
+
+/** Append a decision entry to the growth decisions log. */
+export function logDecision(
+  candidate: CandidateRow,
+  decision: "approved" | "edited" | "skipped",
+  editedReply?: string,
+): void {
+  const dir = dirname(DECISIONS_PATH);
+  if (!existsSync(dir))
+    mkdirSync(dir, {
+      recursive: true,
+    });
+
+  const date = new Date().toISOString().split("T")[0];
+  const reply = editedReply ?? candidate.draftReply;
+  const entry = `
+## ${decision.toUpperCase()} — ${date}
+
+- **Post**: [${candidate.title}](https://reddit.com${candidate.permalink})
+- **Subreddit**: r/${candidate.subreddit}
+- **Decision**: ${decision}
+${editedReply ? "- **Edited**: yes (original draft was modified)\n" : ""}\
+- **Reply**: ${reply.replace(/\n/g, " ")}
+
+---
+`;
+
+  appendFileSync(DECISIONS_PATH, entry);
+}
+
+/** Read the decisions log (returns empty string if no file). */
+export function readDecisions(): string {
+  if (!existsSync(DECISIONS_PATH)) return "";
+  return readFileSync(DECISIONS_PATH, "utf-8");
+}
+
 // #endregion
 
 // #region Claude Code stream parsing

.claude/skills/setup-spa/main.ts

@@ -14,12 +14,14 @@ import {
   findCandidate,
   findThread,
   formatToolStats,
+  logDecision,
   markdownToRichTextBlocks,
   openDb,
   PR_URL_REGEX,
   parseStreamEvent,
   plainTextFallback,
   ResultSchema,
+  readDecisions,
   runCleanupIfDue,
   stripMention,
   updateCandidateStatus,
@@ -1042,6 +1044,7 @@ app.action("growth_approve", async ({ ack, body, client }) => {
         postedReply: candidate.draftReply,
         redditCommentUrl: commentUrl,
       });
+      logDecision(candidate, "approved");
       // Update the Slack message — replace buttons with confirmation
       if (candidate.slackChannel && candidate.slackTs) {
         await replaceButtonsWithStatus(
@@ -1184,6 +1187,7 @@ app.view("growth_edit_submit", async ({ ack, view, body, client }) => {
         postedReply: editedReply,
         redditCommentUrl: commentUrl,
       });
+      logDecision(candidate, "edited", editedReply);
       if (candidate.slackChannel && candidate.slackTs) {
         await replaceButtonsWithStatus(
           client,
@@ -1230,6 +1234,7 @@ app.action("growth_skip", async ({ ack, body, client }) => {
     status: "skipped",
     actionedBy: userId,
   });
+  logDecision(candidate, "skipped");
 
   if (candidate.slackChannel && candidate.slackTs) {
     await replaceButtonsWithStatus(