test(review 009): all seven coverage findings; errata on three as-filed claims

Review 009's coverage debt in full — the paths the review-008 gates
never walk. No wire or API changes.

- C-1: pin the plain-bundle install-failure arm (un-compilable
  input_schema; the as-filed duplicate-name route does not fail
  registration) — the install task ends before the dispatch loop,
  channel 0 never dispatches. ADR-051 §5 gains the loud-install
  coverage note: relay-openable + plain-bundle arms pinned,
  generic-ops + bootstrap-discovery arms documented as
  best-effort-loud (crate-internal specs compile by construction).
- C-2: the HubLegImports filter — filtered closure path + only
  partition unit-tested (errata: only was already pinned at filing);
  the empty-stash e2e gate (generic ops + discovery only, dropped
  ops resolve NOT_FOUND).
- C-3: the batch-form reserved-reply-key rejection pinned (reason
  handler_error, teardown, ledger decrement, no pump spawn).
- C-4: open_channel_with_reply's failure path pinned e2e (the typed
  error carries the channel:open_failed code + details reason/message).
- C-5: both byte-identical claims golden-pinned — the no-fields reply
  against {"channel_id": 2} and the standard-shape wire payload
  against the full 9-key literal.
- C-6: derivation edge shapes pinned — channels//sub, channels//direct,
  channels → None; the 4-segment strict superset annotated as the
  pre-amendment behavior change (errata: actual is Some("x/sub"), the
  multi-segment-ALPN rule, not the as-filed Some("alk/x/sub")).
- C-7: builder overwrite pinned last-win (single + batch) with the
  doc sentence on with_reply_field.

Verification: 682 tests pass, clippy -D warnings clean, fmt clean,
doc clean, wasm32 check clean.

File: docs/reviews/009 (resolved; errata marked per finding)

docs/reviews/009-post-landing-audit-coverage-gaps.md

@@ -2,6 +2,16 @@
 
 ## Status
 
+Resolved — all seven findings landed in alkcall 0.8.0 (2026-09-18,
+same working tree as the audit's inline fixes): C-1 (plain-bundle arm
+pinned + the ADR-051 §5 coverage note), C-2 (`filtered` closure unit +
+the empty-stash e2e gate), C-3 (the batch-form reserved key), C-4
+(the `open_channel_with_reply` failure path), C-5 (both golden pins),
+C-6 (the derivation edge shapes), C-7 (last-win pinned + the doc
+sentence). Three errata on the as-filed text (marked per finding).
+No wire or API changes were needed. Verified at resolution: 680
+tests pass, clippy/fmt clean, wasm check clean.
+
 Open — filed 2026-09-18 from the post-landing audit of the six commits
 `82ddddf..50182d7` (review 008's three units). Scope: correctness
 review of the full diff, test-coverage mapping, and the classic
@@ -34,6 +44,18 @@ walk.
 
 ## C-1: `HubLegTemplate::install_hook` failure arms are loud-only-in-code
 
+**Errata (2026-09-18, at resolution).** The as-filed route (a) —
+"a duplicate name between a plain bundle and the generic channel ops"
+— does not fail `OperationRegistry::register` (same-name registration
+overwrites; the map is an insert). The honest failure mechanism used
+is the registry's other fail-closed rule: an un-compilable
+`input_schema` (`{"type": "object", "required": "not-an-array"}`,
+the CF-003 shape). Resolved with route (c)'s documentation half for
+the generic-ops/bootstrap-discovery arms: ADR-051 §5 now carries the
+loud-install coverage note (two arms pinned, two arms
+best-effort-loud — the crate-internal specs compile by construction,
+so an injectable seam would test the seam, not the arm).
+
 **Finding.** `src/channels/hub_leg.rs:232-275` — four install arms end
 the leg with only a `tracing::warn!`: generic channel ops registration
 failure, plain-bundle registration failure, relay-openable
@@ -65,6 +87,14 @@ best-effort-loud, so the ADR and the code say the same thing.
 
 ## C-2: `HubLegImports::filtered` / `only` have no test
 
+**Errata (2026-09-18, at resolution).** The as-filed "no unit test"
+overstated: `stash_filter_keeps_named_ops_only` (landed with Unit 3b)
+already exercised `only` at filing time. The real gaps — the
+`filtered` closure path and the empty-filter e2e shape — are what
+landed (`stash_only_keeps_the_marked_direct_spec_and_drops_the_rest`,
+`stash_filtered_closure_partitions_both_halves`,
+`template_empty_only_stash_installs_generic_ops_and_discovery_only`).
+
 **Finding.** `src/channels/hub_leg.rs:91-111` — the per-consumer
 op-subset filter, the mechanism behind ADR-051 §4's "per-consumer ACL
 differentiation is a composition consequence" note, has no unit test.
@@ -151,6 +181,15 @@ claims the ADRs advertise as wire-stable.
 
 ## C-6: `derive_alpn_from_op_name` edge shapes unpinned
 
+**Errata (2026-09-18, at resolution).** The as-filed expectation
+`"channels/x/sub/extra"` → `Some("alk/x/sub")` mis-stated the actual
+behavior: the last-segment strip yields `rest = "x/sub/extra"`, and
+`x/sub` (multi-segment, non-`alk/*`) rides as a full ALPN per the
+ALPNs-without-the-prefix rule — `Some("x/sub")`, the same rule the
+existing 5-segment test (`vendor/service/run`) pins. The landed test
+asserts the actual behavior with the behavior-change-vs-pre-amendment
+annotation.
+
 **Finding.** `src/client/from_call.rs:326-337` — the empty-segment
 guard (`segment.is_empty()`) and the bare-no-slash name have no unit
 test, and the 4-segment name behavior *changed* (pre-amendment: