docs: reserve seam for complete capabilities

.agents/notes/implemented/feature/2026-07-26-code-dispatch-log-spill.md

@@ -14,8 +14,8 @@ Since the full-content dispatch logging landed, a `run_code` program that reads
 
 **A log-shaping waterfall on the registry, and the spill policy as its first listener.**
 
-- **Seam**: `tools/code-dispatch-log` — a scope-filtered waterfall the bridge runs (via the registry's PRIVATE `shapeDispatchLog` invoker, handed to the bridge as a capability closure in `RunCodeBridgeOptions` — the waterfall is the public seam, the invoker never widens the service surface; contained: a throwing listener falls back to the unshaped content, with total error formatting so a hostile thrown value cannot escape the containment) over each settled sub-dispatch before appending `tool/code-dispatch`. The payload (`CodeDispatchLog`) carries the outer execution, the hoisted `agent` routing key, the sub-call identity, and the default content — the RENDERED result projection a native `tool/result` would carry (the program itself received the structured `value`). Only the durable copy is shapeable; the model sees neither. Shaping runs OFF the program path as tracked side work, but bounded: past `maxParallelSubCalls` pending log tasks the ordered commit lane holds, so a slow spill backend backpressures the run instead of accumulating unbounded pending I/O; run settlement still drains every task inside the open turn.
-- **Policy**: `dsh-spill-policy` registers a second arm on the new seam sharing the exact replacement pipeline of its model-facing arm (same `maxInlineBytes` cap, same preview + locator + within-cap invariant, same best-effort fallbacks), with the artifact labeled `dispatch` under the sub-call id. UIs and replay read the full text through the spill artifact exactly as they do for spilled native results, so the native-parity rendering story survives bounding.
+- **Extension point**: `tools/code-dispatch-log` — a scope-filtered waterfall the bridge runs (via the registry's PRIVATE `shapeDispatchLog` invoker, handed to the bridge as a capability closure in `RunCodeBridgeOptions` — the waterfall is the public contract, the invoker never widens the service surface; contained: a throwing listener falls back to the unshaped content, with total error formatting so a hostile thrown value cannot escape the containment) over each settled sub-dispatch before appending `tool/code-dispatch`. The payload (`CodeDispatchLog`) carries the outer execution, the hoisted `agent` routing key, the sub-call identity, and the default content — the RENDERED result projection a native `tool/result` would carry (the program itself received the structured `value`). Only the durable copy is shapeable; the model sees neither. Shaping runs OFF the program path as tracked side work, but bounded: past `maxParallelSubCalls` pending log tasks the ordered commit lane holds, so a slow spill backend backpressures the run instead of accumulating unbounded pending I/O; run settlement still drains every task inside the open turn.
+- **Policy**: `dsh-spill-policy` registers a second arm on the new extension point sharing the exact replacement pipeline of its model-facing arm (same `maxInlineBytes` cap, same preview + locator + within-cap invariant, same best-effort fallbacks), with the artifact labeled `dispatch` under the sub-call id. UIs and replay read the full text through the spill artifact exactly as they do for spilled native results, so the native-parity rendering story survives bounding.
 - **One deliberate asymmetry**: the model-facing arm skips `read` (the `read → spill → read again` loop); the dispatch-log arm bounds `read` sub-calls too — a log copy is not model context, so the loop cannot happen, and `read` is precisely the tool that produces huge logs.
 
 ## Alternatives considered