fix(codemode): bound eval status history

[minpeter]

Summary

• bound Code Mode eval status history to 100 rows per cell
• reserve one row for an exact omitted-event count after overflow
• retain the newest 99 real events without changing normal small histories or agent-status coalescing
• document the bounded-history contract in the package README and changelog

This PR is deliberately independent and based directly on current main; it has no compaction lifecycle or TUI
dependency. It supersedes the old fork-only third PR in that stack.

Root cause

Each eval cell kept every emitted status event in state.events. Read/update-heavy child work could emit thousands of
events, and every render rebuilt the full unbounded list. A long session could therefore retain and repeatedly render
enough history to drive V8 toward its heap limit.

Behavior

• at most 100 retained status rows per cell
• after overflow: one synthetic omission row plus the newest 99 events
• exact omitted-event count remains correct as additional events arrive
• small histories and existing coalescing behavior remain byte-for-byte unchanged

Verification

• focused status/render/tool-output regressions
• full senpi-codemode package suite and root build/check
• real low-heap 125-read and 20,000-read scenarios
• exact retained row and omitted-count assertions

Fresh validation receipts will be attached to this Draft before it is marked ready.

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Summary by cubic

Bound each eval cell’s status history in senpi-codemode to 100 entries to prevent unbounded growth and costly re-renders. Updated renderer, tests, and docs accordingly.

• Bug Fixes
  • Limit per-cell history to 100; after overflow, keep one “earlier events omitted” row plus the latest 99.
  • Maintain an exact omitted-event count as more events arrive; small histories and agent-status coalescing remain unchanged.
  • Add renderer support for the new status-events-omitted op (e.g., “26 earlier events omitted”).
  • Add tests for partial/final details and bounds; document the bounded history in README and CHANGELOG.

^{Written for commit 98e7ca6. Summary will update on new commits.}

[minpeter]

Superseded by verified current-main Draft #334. The replacement is based directly on main@38bd3a3cf, carries patch-identical minimal commits, and passed the root build/check, scoped Code Mode tests, and real 256 MB source-CLI QA at 20,000 status events. Closing this stale branch only after confirming #334 live with the verified head SHA.

[minpeter]

Superseded by #335, the clean replacement based directly on current main at 38bd3a3.