Merge origin/main, resolve CHANGELOG conflict, bump to v0.13.7.0

Main landed v0.13.6.0 (GStack Learns) while this branch had v0.13.6.0
(Community Wave). Resolved by keeping both entries and bumping this
branch to v0.13.7.0. Regenerated SKILL.md files to pick up new learn
skill and apply the find -exec rm fix from this branch.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

investigate/SKILL.md

@@ -77,6 +77,15 @@ for _PF in $(find ~/.gstack/analytics -maxdepth 1 -name '.pending-*' 2>/dev/null
   fi
   break
 done
+# Learnings count
+eval "$(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null)" 2>/dev/null || true
+_LEARN_FILE="${GSTACK_HOME:-$HOME/.gstack}/projects/${SLUG:-unknown}/learnings.jsonl"
+if [ -f "$_LEARN_FILE" ]; then
+  _LEARN_COUNT=$(wc -l < "$_LEARN_FILE" 2>/dev/null | tr -d ' ')
+  echo "LEARNINGS: $_LEARN_COUNT entries loaded"
+else
+  echo "LEARNINGS: 0"
+fi
 ```
 
 If `PROACTIVE` is `"false"`, do not proactively suggest gstack skills AND do not
@@ -371,6 +380,44 @@ Gather context before forming any hypothesis.
 
 4. **Reproduce:** Can you trigger the bug deterministically? If not, gather more evidence before proceeding.
 
+## Prior Learnings
+
+Search for relevant learnings from previous sessions:
+
+```bash
+_CROSS_PROJ=$(~/.claude/skills/gstack/bin/gstack-config get cross_project_learnings 2>/dev/null || echo "unset")
+echo "CROSS_PROJECT: $_CROSS_PROJ"
+if [ "$_CROSS_PROJ" = "true" ]; then
+  ~/.claude/skills/gstack/bin/gstack-learnings-search --limit 10 --cross-project 2>/dev/null || true
+else
+  ~/.claude/skills/gstack/bin/gstack-learnings-search --limit 10 2>/dev/null || true
+fi
+```
+
+If `CROSS_PROJECT` is `unset` (first time): Use AskUserQuestion:
+
+> gstack can search learnings from your other projects on this machine to find
+> patterns that might apply here. This stays local (no data leaves your machine).
+> Recommended for solo developers. Skip if you work on multiple client codebases
+> where cross-contamination would be a concern.
+
+Options:
+- A) Enable cross-project learnings (recommended)
+- B) Keep learnings project-scoped only
+
+If A: run `~/.claude/skills/gstack/bin/gstack-config set cross_project_learnings true`
+If B: run `~/.claude/skills/gstack/bin/gstack-config set cross_project_learnings false`
+
+Then re-run the search with the appropriate flag.
+
+If learnings are found, incorporate them into your analysis. When a review finding
+matches a past learning, display:
+
+**"Prior learning applied: [key] (confidence N/10, from [date])"**
+
+This makes the compounding visible. The user should see that gstack is getting
+smarter on their codebase over time.
+
 Output: **"Root cause hypothesis: ..."** — a specific, testable claim about what is wrong and why.
 
 ---
@@ -494,6 +541,30 @@ Status:          DONE | DONE_WITH_CONCERNS | BLOCKED
 ════════════════════════════════════════
 ```
 
+## Capture Learnings
+
+If you discovered a non-obvious pattern, pitfall, or architectural insight during
+this session, log it for future sessions:
+
+```bash
+~/.claude/skills/gstack/bin/gstack-learnings-log '{"skill":"investigate","type":"TYPE","key":"SHORT_KEY","insight":"DESCRIPTION","confidence":N,"source":"SOURCE","files":["path/to/relevant/file"]}'
+```
+
+**Types:** `pattern` (reusable approach), `pitfall` (what NOT to do), `preference`
+(user stated), `architecture` (structural decision), `tool` (library/framework insight).
+
+**Sources:** `observed` (you found this in the code), `user-stated` (user told you),
+`inferred` (AI deduction), `cross-model` (both Claude and Codex agree).
+
+**Confidence:** 1-10. Be honest. An observed pattern you verified in the code is 8-9.
+An inference you're not sure about is 4-5. A user preference they explicitly stated is 10.
+
+**files:** Include the specific file paths this learning references. This enables
+staleness detection: if those files are later deleted, the learning can be flagged.
+
+**Only log genuine discoveries.** Don't log obvious things. Don't log things the user
+already knows. A good test: would this insight save time in a future session? If yes, log it.
+
 ---
 
 ## Important Rules

investigate/SKILL.md.tmpl

@@ -60,6 +60,8 @@ Gather context before forming any hypothesis.
 
 4. **Reproduce:** Can you trigger the bug deterministically? If not, gather more evidence before proceeding.
 
+{{LEARNINGS_SEARCH}}
+
 Output: **"Root cause hypothesis: ..."** — a specific, testable claim about what is wrong and why.
 
 ---
@@ -183,6 +185,8 @@ Status:          DONE | DONE_WITH_CONCERNS | BLOCKED
 ════════════════════════════════════════
 ```
 
+{{LEARNINGS_LOG}}
+
 ---
 
 ## Important Rules