End-of-session: transcript tracking log, context update, README docs

- Add session log (2026-04-13) covering transcript backup tracking system
- Add context/transcript-tracking.md: first-run verification checklist for
  the Sonnet subagent path in /log
- Update CONTEXT.md with transcript tracking entry
- Update README.md: document extract-transcripts.py and list-transcripts-here.sh;
  note that install-hooks.sh now covers skill-helper scripts too
- Prune 3 reflected logs older than retention_days (7): 2026-03-23, -25, -29

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

memory/log/2026-04-13.140716.md

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+# Session Log — 2026-04-13
+
+## Summary
+
+Built a complete pre-compaction transcript backup tracking system: fixed the broken `pre-compact-backup.sh` hook, created `extract-transcripts.py` and `list-transcripts-here.sh`, updated the `/log` skill to dispatch a Sonnet subagent for transcript analysis, moved all scripts to their canonical homes in claude-foundations, and ensured both active profiles are in sync.
+
+## Decisions
+
+- Decision: Use Sonnet (not Haiku) for transcript analysis subagent in `/log` — Rationale: gotcha detection requires judgment about backtracking and failed attempts; Haiku tends to see only the final outcome and miss the failure mode that led to it
+- Decision: `/log` pre-gathers only transcript metadata (compact JSON) not content — Rationale: full transcript content would overflow context; content reading delegated to the Sonnet subagent in its own fresh context window
+- Decision: Tracking file at `~/.claude/transcript-backups/tracking.json` (machine-readable JSON) — Rationale: both hook (bash) and skill (python) need to update it; JSON is simpler to parse than markdown tables from bash
+- Decision: Scripts live in `claude-foundations/scripts/`, symlinked to `~/.claude/scripts/` — Rationale: consistent with hooks pattern; `~/.claude/scripts/` is a fixed path accessible from all profiles since `~/.claude/` always resolves to the default profile dir
+- Decision: `install-hooks.sh` extended with a curated `SKILL_HELPERS` array to manage skill-helper script symlinks — Rationale: not all claude-foundations scripts belong in `~/.claude/scripts/`, only ones referenced by skills
+
+## Gotchas Discovered
+
+- **[hooks]** Symptom: `pre-compact-backup.sh` was silently skipping every run — Fix: Claude Code's PreCompact hook no longer provides `transcript_path` in the JSON input (changed from older versions); derive path from `session_id` + `cwd` using `~/.claude/projects/$(cwd | tr '/' '-')/<session_id>.jsonl`
+- **[python]** Symptom: cwd extraction loop printed multiple lines instead of stopping at first match — Fix: `sys.exit(0)` inside `except: pass` is caught as `SystemExit`; use a `break` or don't use bare `except` when early exit is needed inside exception handlers
+- **[skills]** Symptom: SKILL.md validator error on bang command using `$(pwd)` — Fix: `$()` substitution in SKILL.md bang commands is rejected by the Claude Code permission checker; create a wrapper shell script that runs `$(pwd)` internally and call the wrapper from the bang command instead
+
+## Key Context
+
+- Old transcript backups with `-auto` suffix (before tracking system) are not in `tracking.json` and will never appear in `--list`; they'll be pruned by the 30-day cleanup in the hook
+- Profile parity fix: `~/.claude-octopus/skills/switch-mode` symlink was missing; added
+- `~/.claude/scripts/` is the canonical location for skill-helper scripts; `~/.claude/` always resolves to the default profile dir, making it accessible from all profiles regardless of `CLAUDE_CONFIG_DIR`
+- The Sonnet subagent in `/log` writes to the project's absolute `memory/log/` path — worth verifying on first real run that it uses the absolute path correctly, not a relative one from the wrong cwd