fix(session-end): skip end marker for empty sessions

[sasha-id]

Summary

The session-end hook unconditionally posts a [Session ended] Reason: ${reason}, Messages: ${count}, Time: ${iso} marker to Honcho on every termination, including sessions with zero transcript messages (e.g. resumed but never used). Honcho's deriver then extracts these markers as durable memory observations, e.g.:

• "<peer>'s session ended on May 7, 2026, at 00:18:47 UTC"
• "The session <peer> ended on May 7, 2026, contained zero messages"

These have no future-recall value — they're session-plumbing exhaust extracted as user/AI facts — and each one costs deriver LLM tokens.

What this changes

Gates endMarker creation behind transcriptMessages.length > 0 in plugins/honcho/src/hooks/session-end.ts.

• Side-channel queued messages (e.g. [Git External] from session-start, queued user prompts) still upload normally — only the lifecycle marker is suppressed.
• The existing if (allMessages.length > 0) guard handles the fully-empty case and skips the upload entirely.
• API-call log line now reflects whether a marker was included or skipped.

Why minimal

The fix is intentionally narrow. Non-empty sessions still get their end markers (preserves session-end timestamps in memory). Only the zero-message lifecycle artifact — the one with no signal at all — is dropped.

Test plan

• bunx tsc --noEmit clean
• Manual smoke test on local install (multi-profile Hermes setup with frequent Claude Code resumes)
• Reviewer to validate against any test additions in stacked PRs (this branch is based directly on main and ships no new tests; config.test.ts is added by feat(config): HONCHO_PROFILE env var for per-session identity routing #33/feat(config): HONCHO_SESSION env var for per-launch session pinning #36)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Session-end hook now skips emitting the session-ended marker when sessions contain no transcript messages, while continuing to upload other queued messages as expected.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 7b0d593d-2538-4664-a62d-f9017e06a38c

📥 Commits

Reviewing files that changed from the base of the PR and between 0813ebd and 1ea3f39.

📒 Files selected for processing (2)

• CHANGELOG.md
• plugins/honcho/src/hooks/session-end.ts

---

Walkthrough

The session-end hook is updated to conditionally suppress the [Session ended] marker when a session contains zero transcript messages. Side-channel queued messages continue uploading normally; only the marker extraction is gated for empty sessions.

Changes

Session-End Empty Marker Suppression

Layer / File(s)	Summary
Core Logic plugins/honcho/src/hooks/session-end.ts	handleSessionEnd now creates the [Session ended] marker only when transcriptMessages.length > 0. For empty sessions, the marker is set to null and omitted from the final payload, while other queued messages remain unaffected. Logging updated to reflect marker inclusion status.
Documentation CHANGELOG.md	Changelog entry added under [Unreleased] → Fixed documenting the new behavior that prevents durable-memory marker emission for empty sessions.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 An empty session whispers low,
No marker needed—silence, though!
The side-channel flows, messages stay,
While phantom endings fade away. ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix(session-end): skip end marker for empty sessions' accurately and specifically summarizes the main change: conditionally skipping the end marker for empty sessions.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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