fix(deriver): clear dangling session hint on pending dreams at session delete

[Rajat-Ahuja1997]

What

delete_session now strips payload.session_name from pending dream queue items that reference the session being deleted.

Why

Surfaced while reviewing #801 / #799. delete_session already deletes the session's QueueItem and ActiveQueueSession rows, but dreams slip through both:

• Dream records carry session_id=None (src/deriver/enqueue.py:441), so the session_id delete misses them.
• The dream work-unit key is dream:{dream_type}:{workspace}:{observer}:{observed} — no session component — so the split_part(key, ':', 3) == session_name match misses them too.

A dream isn't scoped to a session in the first place: it consolidates the whole (observer, observed) collection. payload.session_name is only a config/context hint, set by DreamScheduler._execute_dream to the session of the most recent explicit document for that pair (src/dreamer/dream_scheduler.py:195-205).

So the stale row isn't stale work — it's a stale tag. Left alone, run_dream resolves that session for configuration (src/dreamer/orchestrator.py:112), raises ResourceNotFoundException, and the dream errors out for no good reason.

How

Clear the hint rather than delete the dream, leaving it workspace-scoped — a state the orchestrator already handles (session_name is None → workspace config), and one the manual dream route produces whenever session_id is omitted (src/routers/workspaces.py:232).

Scoped to processed = false; historical rows are left to the reconciler.

Testing

tests/crud/test_session.py::TestSessionCRUD::test_delete_session_clears_dangling_dream_session_hint — three dreams (one on the deleted session, one on another session, one workspace-wide); asserts all three survive and only the first loses its hint. Fails without the fix.

uv run pytest tests/crud/ tests/routes/test_sessions.py → 116 passed.

Summary by CodeRabbit

• Bug Fixes

  • Deleting a session now removes its reference from related unprocessed dream queue items without deleting those items.
  • Unrelated session-linked and global dream items remain unchanged.

• Tests

  • Added regression coverage to verify queue item preservation and correct cleanup of deleted session references.

[coderabbitai]

Walkthrough

Session deletion now removes payload.session_name from matching unprocessed workspace-scoped dream queue items. The queue items remain. A regression test verifies that unrelated dream records are unchanged.

Changes

Session deletion cleanup

Layer / File(s)	Summary
Queue payload cleanup src/crud/session.py	Session deletion updates matching unprocessed dream queue item payloads and removes session_name without deleting the items.
Cleanup regression test tests/crud/test_session.py	The asynchronous test verifies selective cleanup across two sessions and three dream queue items.

Estimated code review effort: 2 (Simple) | ~10 minutes

Poem

I’m a rabbit guarding the queue,
Session hints vanish, but dreams stay true.
One trail clears, the others remain,
No dangling names hop back again.
Thump, thump—the test confirms the change!

🚥 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 clearly summarizes the main change: clearing dangling session hints from pending dreams when a session is deleted.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch rajat/delete-session-dream-queue-items

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[coderabbitai]

🧹 Nitpick comments (1)

tests/crud/test_session.py (1)

200-209: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Cover processed records and JSON key removal.

Lines 202-209 treat a missing session_name key and session_name: None as the same result. Add a processed dream with test_session.name and assert that it retains its hint. Assert that "session_name" is absent from the unprocessed target payload. This validates the required preservation of historical rows and the JSONB key-removal behavior.

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@tests/crud/test_session.py` around lines 200 - 209, Extend the dream
fixture/assertion coverage around the existing payload-comprehension assertion
to include a processed dream referencing test_session.name and verify that its
session hint remains unchanged. Separately assert that the unprocessed
deleted-session dream’s payload does not contain the “session_name” key,
distinguishing JSONB key removal from a present None value.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@tests/crud/test_session.py`:
- Around line 200-209: Extend the dream fixture/assertion coverage around the
existing payload-comprehension assertion to include a processed dream
referencing test_session.name and verify that its session hint remains
unchanged. Separately assert that the unprocessed deleted-session dream’s
payload does not contain the “session_name” key, distinguishing JSONB key
removal from a present None value.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

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Run ID: 95e99290-3f98-49ca-8c3e-44813314a6e9

📥 Commits

Reviewing files that changed from the base of the PR and between d191c10 and b13e4f7.

📒 Files selected for processing (2)

• src/crud/session.py
• tests/crud/test_session.py