fix(memory): surface honest notice for bodyless session reads

[khustup2]

Summary

A session cat through the memory mirror could return 0 bytes with no signal while ls showed a non-zero size — making the mirror look populated when the transcript body was actually unreadable, and blocking fallback to raw session data for turn-level detail.

Root cause, both plugin-side (backend unchanged):

1. Silent-empty reconstruction. A captured event is never legitimately empty (capture.ts always writes a populated JSON entry), so a session that reconstructs to "" is always a pathology — but both readers returned it as an empty file. ls size comes from a separate MAX(size_bytes) query, so it stayed non-zero → the misleading size-vs-content split.
2. Fragile null handling. normalizeSessionMessage did JSON.stringify(message) unconditionally: a NULL column became the literal text "null", and undefined leaked into the joined output.

Fix:

• grep-core.ts — shared emptySessionBodyNotice(rowCount): honest diagnostic ("rows exist, body empty, metadata only — not an empty file").
• virtual-table-query.ts (hook path — what Claude Code's bash cat hits) — count session rows even when message::text is NULL (previously dropped silently), skip empty normalized parts, emit the notice instead of "" (silent empty) or null (misleading "No such file" though ls lists it).
• deeplake-fs.ts (shell path) — normalizeSessionMessage coerces null/undefined/non-serializable → ""; joinSessionMessages filters empty parts; prefetch/readFile/readFileBuffer emit the notice on empty reconstruction.

Scope note: this makes the empty-read case honest, not silent — it does not change why a body would be empty (a separate capture/storage question, answerable per-row via length(message::text) vs size_bytes).

Version Bump

Bug fix → warrants a patch bump (0.7.126 → 0.7.127). Not bumped yet — package.json is unchanged, so as-is this merges with no release. Will bump on request to ship it.

Test plan

• Tests pass locally (npx vitest run on affected suites: 376 passed — deeplake-fs, virtual-table-query, grep-core, pre-tool-use)
• Relevant new tests added (7: NULL / undefined / empty-string bodies, no-"null"/"undefined"-leak guarantee, mixed empty+real turns across both reader paths)
• Version bumped in package.json, or no release needed for this change — pending decision (see Version Bump)

🤖 Generated with Claude Code

[coderabbitai]

📝 Walkthrough

Walkthrough

Session-backed virtual and filesystem reads now distinguish stored rows with empty or null bodies from missing files, filter unusable message parts, and return a row-count-aware empty-body notice. Tests cover empty, nullish, and mixed session messages.

Changes

Session body handling

Layer / File(s)	Summary
Empty-body diagnostic helper src/shell/grep-core.ts	Adds emptySessionBodyNotice(rowCount) for sessions containing metadata rows without usable message bodies.
Virtual path session reconstruction src/hooks/virtual-table-query.ts, tests/claude-code/virtual-table-query.test.ts	Counts session rows independently of content validity, returns an empty-body notice when all bodies are unusable, and retains only non-empty turns in mixed sessions.
Filesystem session rendering src/shell/deeplake-fs.ts, tests/claude-code/deeplake-fs.test.ts	Normalizes nullish messages, filters empty parts, applies notices during prefetch and file reads, and tests null, undefined, empty, and mixed bodies.

Estimated code review effort: 3 (Moderate) | ~20 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
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.
Title check	✅ Passed	The title is concise and accurately summarizes the main change: surfacing an honest notice for bodyless session reads.
Description check	✅ Passed	The description follows the template with Summary, Version Bump, and Test plan sections, and includes the key implementation and testing details.

✨ 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 fix/session-empty-body-honest-read

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[github-actions]

Coverage Report

Scope: files changed in this PR. Enforced threshold: 90% per metric (per file via vitest.config.ts).

Status	Category	Percentage	Covered / Total
🟢	Lines	99.23% (🎯 90%)	899 / 906
🟢	Statements	97.16% (🎯 90%)	1061 / 1092
🟢	Functions	97.12% (🎯 90%)	135 / 139
🟢	Branches	91.10% (🎯 90%)	860 / 944

File Coverage — 3 files changed

File	Stmts	Branches	Functions	Lines
src/hooks/virtual-table-query.ts	🟢 98.7%	🟢 92.3%	🟢 95.8%	🟢 99.2%
src/shell/deeplake-fs.ts	🟢 96.4%	🟢 90.5%	🟢 97.2%	🟢 98.8%
src/shell/grep-core.ts	🟢 97.8%	🟢 91.5%	🟢 97.7%	🟢 100.0%

_{Generated for commit c6a003e.}