fix(x): stop KG agent from rewriting meeting notes; gate People notes on calendar attendees

[arkml]

Problem

Two user-reported bugs, root-caused via the knowledge repo's git history:

1. Meeting summaries destroyed. The note_creation agent treated knowledge/Meetings/ as one of its own writable note types (an empty "Meetings" template was rendered into its prompt, and nothing marked source files read-only). On the graph tick after a meeting ended it rewrote the recorded note into an invented entity format, replacing the detailed summary + transcript with ~3 lines. Git evidence: Research_reading.md went 60KB → 1,073 bytes mid-recording (only the recorder's 1s debounced rewrite restored it), and the agent fabricated a duplicate meeting-<timestamp>.md entity note alongside it.
2. Phantom people. Meeting notes were processed while still being recorded (the file changes every ~1s, so every 15s tick re-ran the LLM on the growing transcript — ~20 runs in one meeting), minting People notes from speech-recognition name variants: one attendee "Shubham" became Shubham.md, Shubhrant.md, and Shivam.md, plus 47-byte stubs for other misheard names.

Fixes

Meeting sources are read-only to the KG agent (prompt + mechanical guard)

• Empty-template note types (Meetings) no longer render into the agent prompt (note_system.ts)
• New non-negotiable prompt rules: source files are read-only; there is no "meeting note" type to create or update (note_creation.ts, batch message in build_graph.ts)
• revertAgentSourceWrites backstop: a Pre-agent snapshot commit runs before every agent batch; any agent write under knowledge/Meetings/, knowledge/Voice Memos/, gmail_sync/, or knowledge_sources/ is restored from the batch snapshot / git HEAD, or deleted if the agent created it (deletion requires the repo to have a HEAD commit, so a fresh install can never lose data). Reverts surface as warn service-log events. Wired into both the main batch loop and the voice-memo loop.

In-flight recordings are held

• MEETING_NOTE_QUIET_MS (6 min, above the recorder's 5-min silence backstop): meeting-source files are skipped until they stop changing — one LLM run per meeting instead of ~20, and no partial-transcript processing.

People notes anchored to the calendar invite

• The recorder stamps the invite's attendees ("Name <email>") into the note's calendar_event frontmatter, resolved from the linked event file or passed through from the detector/notification flow (useMeetingTranscription.ts, App.tsx, calendar-block.tsx)
• meetingAttendeesBanner stamps an authoritative ATTENDEES-GATE onto each rowboat-recorded source (frontmatter attendees → linked event file → calendar_sync scan by exact title+start): new People notes only for listed attendees — teammates on the invite included; similar-sounding transcript names resolve to ONE attendee's note (variant spellings go to Aliases); ad-hoc recordings with no invite create no People notes at all, though names still appear in summaries
• Granola/Fireflies notes are not gated (platform-reported attendee lists are trusted)

Testing

• npm run deps, npm run typecheck clean; lint errors are pre-existing in untouched files
• 536/536 core tests pass, including 3 new meetingAttendeesBanner tests (non-rowboat sources ignored, stamped attendees listed, ad-hoc → no-People banner)

🤖 Generated with Claude Code

[arkml]

Follow-up commit (0206b0f) for uninvited joiners — people who join a meeting without being on the invite:

• Summary: may name them when the transcript clearly supports it (introduced/addressed by that name repeatedly), using one canonical spelling for similar-sounding ASR variants; a name heard once or inconsistently stays "They".
• Knowledge graph: an off-list name that clearly matches an existing People note may update that note (so a teammate who drops in still accrues the meeting on their note); creating a new note for anyone off the invite remains forbidden.

🤖 Generated with Claude Code