feat(session-ingest): export session diffs

[iscekic]

Summary

Export the latest session_diff payload from session ingest as a top-level sessionDiff field so clients can restore filesystem state without scraping message summaries. Update the cloud-agent restore wrapper to prefer that top-level diff payload, apply patch-backed diffs with git apply --3way, and retain the existing message-summary fallback for older exports.

Verification

• No UI path to manually verify; this is backend export/restore behavior. The end-to-end CLI import path was verified against a local fake ingest export in the companion Kilo PR.

Visual Changes

N/A

Reviewer Notes

This keeps the ingest export format backward compatible: sessions without a stored diff return sessionDiff: [], and restore still falls back to legacy messages[].info.summary.diffs data.

[kilo-code-bot]

Code Review Summary

Status: No Issues Found | Recommendation: Merge

Executive Summary

The previously flagged WARNING (R2 fallback emitting {} instead of [] for a missing session_diff blob) has been resolved: enqueueItemData now accepts a missingFallback parameter, and the session_diff call site passes '[]', with a new integration test asserting the empty-array output.

Files Reviewed (4 files)

• services/session-ingest/src/dos/SessionIngestDO.ts — fixed (previous WARNING resolved)
• services/session-ingest/test/integration/session-ingest-do.test.ts — new test added
• services/cloud-agent-next/wrapper/src/restore-session.ts — no changes
• services/cloud-agent-next/wrapper/src/restore-session.test.ts — no changes

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_{Reviewed by claude-4.6-sonnet-20260217 · 171,711 tokens}

_{Review guidance: REVIEW.md from base branch main}

[iscekic]

Fixed in debe6c7. enqueueItemData now accepts a fallback payload, the sessionDiff export path passes [] for missing R2-backed diffs, and the integration test covers that missing-blob case.