fix review findings: correct the property-suite invariant description

The dsh-llm property-suite bullet claimed the suite checks an ordered-prefix
contract (the blocks push() returns incrementally are a prefix of final
blocks(), in order) and streaming-vs-one-shot agreement on usage/finish. Both
died with flushReady()/flushRemaining()/generate()/streamBlocks(): the
ordered-prefix guarantee was provided by that flush pair, and push() never
guaranteed it (index 0 opened by a delta then index 1 closed by block-end has
push() return block 1 while final blocks() orders [0, 1] — the returned block
is not a prefix).

Rewrite the bullet to enumerate only what properties.spec.ts actually asserts:
blocks() count <= distinct indices, idempotent re-assembly with message().content
mirroring blocks(), blocks() never throwing and yielding valid tags, and finish
reflecting the last finish chunk (defaulting to stop).

docs/rfc/implemented/testing/2026-06-11-property-based-testing.md

@@ -14,7 +14,7 @@ Example-based tests pin the cases we thought of. The harness's core is protocol-
 
 Adopt `fast-check` (a root devDependency) with one `tests/properties.spec.ts` per protocol-shaped package, generators tuned for *realistic-but-adversarial* inputs (not uniform noise) and `numRuns` kept so the suite stays well under ~10s locally. Failures print a reproducible seed. (The original proposal also sketched a nightly CI job running 100× the iterations; that was not shipped — the property suite runs only in the normal `push`/`pull_request` CI, and a scheduled high-iteration job remains possible future work.)
 
-- **dsh-llm / BlockAssembler:** arbitrary chunk streams (valid + malformed: duplicate indices, stragglers, missing block-start). Invariants: the blocks `push()` returns incrementally are a prefix of the final `blocks()`, in order; partial count ≤ distinct indices; re-assembly idempotent; streaming and one-shot consumers agree on usage and finish.
+- **dsh-llm / BlockAssembler:** arbitrary chunk streams (valid + malformed: duplicate indices, stragglers, missing block-start). Invariants: `blocks()` count ≤ distinct indices seen; re-assembly idempotent (`blocks()` is stable across repeated calls and `message().content` mirrors it); `blocks()` never throws and yields only valid content-block tags; `finish` reflects the last `finish` chunk, defaulting to `{kind:'stop'}` when none arrives.
 - **dsh-session:** arbitrary event logs. Invariants: `deriveMessages` deterministic; replay-from-seed identical; seq strictly monotonic; non-message events never affect derived history; derived content is decoupled from the log.
 - **dsh-tools:** arbitrary `SchemaSpec`. Invariants: JSON Schema `required` equals the `required:true` keys at every level; conversion total; **and the composition with [runtime arg validation](../architecture/2026-06-11-runtime-arg-validation.md)** — generated args satisfying a spec pass `validateArgs`, and targeted corruptions (dropped required key, non-object top level) are rejected. This closes the validator/`InferArgs` drift risk.
 - **dsh-agent-loop:** arbitrary send schedules against a never-exhausting adapter, driven through the `agent/status` settle signal (no wall-clock sleeps). Invariants: no message lost; turn numbers strictly increase; status transitions stay on the legal machine.