Merge branch 'master' into worktree-windows-runtime

packages/spill/spill-local/README.md

@@ -22,6 +22,10 @@ Files land at `<root>/session-<hash>/​<random>-<safeName>`:
 
 Indirectly, through spill consumers that render the local path and `read`/`grep` retrieval guidance.
 
+#### KV Cache effect
+
+No direct invalidation; the named consumer owns any request-prefix changes.
+
 ## Known Limitations and Deferred Work
 
 - **Local spill files persist until external cleanup** — the backend has no session-lifecycle deletion or age-based retention policy, because persisted, resumed, and forked sessions may still reference a path.

packages/spill/spill-policy/README.md

@@ -36,9 +36,17 @@ The policy sees only the FINAL formatted tool result — not a tool's internal r
 
 ### Oversized plain-text result
 
-**What the model sees**: Results at or below `maxInlineBytes`, `read` results, blocked decisions, and results containing non-text blocks are unchanged. An oversized plain-text result becomes a bounded head/tail preview followed by `(Omitted <bytes> bytes. Full formatted result stored at: <locator>. <retrievalHint>)`; storage or ownership failures leave the original result visible.
+#### What the model sees
 
-**Token effect**: A successful replacement is at most `maxInlineBytes` UTF-8 bytes and remains in history until compaction; the full spill text is not resent to the model.
+Results at or below `maxInlineBytes`, `read` results, blocked decisions, and results containing non-text blocks are unchanged. An oversized plain-text result becomes a bounded head/tail preview followed by `(Omitted <bytes> bytes. Full formatted result stored at: <locator>. <retrievalHint>)`; storage or ownership failures leave the original result visible.
+
+#### Token effect
+
+A successful replacement is at most `maxInlineBytes` UTF-8 bytes and remains in history until compaction; the full spill text is not resent to the model.
+
+#### KV Cache effect
+
+Append-only; newly visible content follows the reusable request prefix and does not invalidate existing KV-cache entries.
 
 ## Known Limitations and Deferred Work
 

packages/spill/spill/README.md

@@ -30,6 +30,10 @@ See the [tool output spill RFC](../../../docs/rfc/implemented/architecture/2026-
 
 Indirectly, through spill consumers that render a backend locator and retrieval guidance.
 
+#### KV Cache effect
+
+No direct invalidation; the named consumer owns any request-prefix changes.
+
 ## Known Limitations and Deferred Work
 
 - **The seam has no retrieval or deletion API** — consumers can only render the backend's locator and guidance; lifecycle and access semantics remain backend-specific.