QVAC-17783 fix: scope kv-cache invalidation to deleted key on RPC delete-cache

[maxim-smotrov]

🎯 What problem does this PR solve?

• Deleting a single cache via the delete-cache RPC (removeCache({ kvCacheKey, modelId })) wiped the entire in-memory cachedMessageCounts map, not just entries for the deleted target. Unrelated caches lost their cached message counts and were forced to reprocess history on the next completion.

📝 How does it solve it?

• handleDeleteCache now scopes both invalidations to the actually-removed target:
  • clearCachedMessageCounts(removedPath) — only entries under the deleted directory
  • clearCacheRegistry({ cacheKey, modelId }) — only matching modelId:configHash:cacheKey entries
  • { all: true } branch now also resets the registry (it wasn't being cleared before).
• deleteCache now returns the removed path so the handler can pass it to the message-count cleaner, and uses rm({ recursive: true, force: true }) so a missing dir is not an error. Errors propagate to the handler's existing structured-error wrapper instead of being silently logged.
• clearCacheRegistry rewritten to parse the composite key (modelId:configHash:cacheKey) and exact-match on cacheKey and/or modelId instead of substring matching.
• clearCachedMessageCounts matches by exact key or prefix + path.sep so a deleted directory invalidates only its own entries, not unrelated keys sharing a string prefix.

🧪 How was it tested?

• Manually exercised the delete-cache RPC with { kvCacheKey, modelId } and verified that:
  • message counts for unrelated caches are preserved
  • initializedCaches no longer retains entries for the deleted target
  • subsequent completions on the deleted cache reinitialize cleanly
• Verified { all: true } still wipes everything end-to-end.

[maxim-smotrov]

/review

[github-actions]

Tier-based Approval Status

**PR Tier:** TIER1

**Current Status:** ✅ APPROVED

**Requirements:**
- 1 Team Member approval ✅ (1/1)
- 1 Team Lead OR Management approval ✅ (1/1)



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*This comment is automatically updated when reviews change.*

[simon-iribarren]

Approving as team member — lead (NamelsKing) and opaninakuffo already signed off.

The bug and fix are both well-characterized:

• handleDeleteCache was wiping the entire cachedMessageCounts map on single-key deletes; now scoped to the removed path.
• clearCacheRegistry was substring-matching on the composite key (modelId:configHash:cacheKey) and could false-positive across entries; now parses and exact-matches.
• clearCachedMessageCounts matches on exact key or prefix + path.sep, avoiding the unrelated-prefix-collision class of bugs.
• { all: true } branch now also resets the registry, closing a gap the old code had.
• deleteCache returning the removed path + switching to rm({ recursive: true, force: true }) is the right shape — idempotent on missing dirs and errors surface through the handler's existing structured-error wrapper.

Small diff (+54/-49, 3 files), tightly scoped to the invalidation path. Ship it.