busbar-core-admin: tests drop the busbar-export-prometheus dev-dep; named-map tests resolve on the kernel's scrape double

[MattJackson]

busbar-core-admin's [dev-dependency] on the plugin crate busbar-export-prometheus is removed. PR #502 puts the pinned plugin checkouts into the kind-isolation census, and that exposed this edge as a kind-isolation-ship finding (cleanliness -> export).

Ruling. Coordinator, 2026-10-07: spec BUSBAR-1.6.0.md l.3870 (FIXTURES (3)) and R-FIX3 (l.3894) apply, so the edge is MOVED, not granted. This PR adds no ledger row, no grant and no ceiling change. It strikes the one [[dep]] row whose drain clause this completes.

Stacked on #570 (lane-gb-kernel-plugin-tests). This PR uses that PR's kernel ScrapeDouble, so its diff carries #570's commits until #570 lands.

What changed

• src/tests/tests.rs::linked_export_axis now installs the kernel's stand-in export axis (busbar_kernel::test_support::export_axis::install_export_axis). The axis's scrape double answers module: prometheus as a linked, first-party, one-instance scrape sink. It used to register the real sink's door (busbar_export_prometheus::door::door).
• Cargo.toml: the dev-dependency is dropped (Cargo.lock updated).
• qa/kind-isolation.toml: the busbar-core-admin -> busbar-export-prometheus test row is struck.

Mapping (old path::fn -> new path::fn)

No test moves. Every test below stays at crates/busbar-core-admin/src/tests/tests.rs::<same fn> and now resolves module: prometheus on the double.

old = new	how
test_admin_v1_overlay_reset_named_map_section_reverts_to_base	double
test_admin_v1_overlay_reset_named_map_refuses_a_dangling_reference	double
limit_zero_does_not_produce_a_self_referential_cursor	double
test_admin_v1_named_maps_list_get_and_put_round_trip	double
test_admin_v1_named_map_put_honors_expected_version	double
test_admin_v1_named_map_rejects_an_under_scoped_caller	double
test_admin_v1_identity_provider_refuses_raising_max_admin_scope	double
test_admin_v1_export_put_that_adds_a_route_reports_restart_required	double
test_admin_v1_identity_provider_validates_an_unreferenced_definition	double
test_admin_v1_identity_provider_rejects_an_unknown_module	double
test_admin_v1_identity_provider_delete_rejects_a_dangling_reference	double
test_admin_v1_named_map_put_rejects_what_the_file_parser_rejects	double
test_admin_v1_named_map_read_flags_an_unparseable_overlay_entry	double

No test needed the real sink. Its rendering and 1.5.5 words are proven at the composition root by #570 (crates/busbar/tests/export_scrape_linked_sink.rs, export_settings_refusal_1_5_5.rs). The test count is unchanged.

Red before green. This PR adds no new double: ScrapeDouble is #570's, and its red runs are in #570. Under those mutations (scrape detection off, the grant lending nothing, the one-instance refusal dropped), 9 tests went red.

Proof

Latchkey (large), this branch's head (origin/predev ba985a8 + #570 + this).

• cargo fmt --all --check: exit 0.
• cargo clippy -p busbar-core-admin --all-targets -- -D warnings: exit 0.
• cargo test -p busbar-core-admin --no-fail-fast (unfiltered): exit 0. The lib suite is 450 passed, 0 failed; the other binaries are 2 passed and 0. The base merge-group CI runs on origin/predev are green, so there are no pre-existing failures.
• cargo xtask gate --all:
  • Exit 1, RED in kind-isolation, kind-isolation-ship, ship-ready. Base e107253 is RED in the same three.
  • All 559 row → status pairs are identical to base.
  • kind-isolation-ship:test-deps goes from 22 findings over 48 test edges on base, to 20 over 46 with busbar-kernel: tests drop the plugin dev-deps (export-prometheus, auth-oidc); doubles in-crate, real-plugin proofs at the root #570 alone, to 19 over 45 here. busbar-core-admin -> busbar-export-prometheus is gone from the census (no longer in the row text).
  • kind-isolation:test-deps: 6 findings on base, 6 here, with 45 edges and 27 [[dep]] rows (base: 48 edges, 30 rows).
• cargo xtask gate kind-isolation --selftest: exit 0. cargo xtask selftest: exit 0 (64 gates, every one proven able to go RED). Both are required because qa/kind-isolation.toml is touched.

[MattJackson]

Back to draft automatically: this branch contains #570 (lane-gb-kernel-plugin-tests), which is also ready. Two hops on the same code is duplicate spend (owner rule 2026-10-08). Mark this ready again after #570 merges.

[github-actions]

promote into predev: DENY @7e049173f: 0 failing test row(s), 11 DENY row(s)

DENY rows (11)

gate	row	detail
construction	one-pick-site	3 production call site(s) of 'pick_among(' (ceiling 2): crates/busbar-kernel-egress/src/walk.rs:298; crates/busbar-llm/src/engine/exhaustion/fallback.rs:120; crates/busbar-llm/src/engine/pipeline.rs:8
kind-isolation	kind-isolation:deps	3 finding(s), 94 shipped edge instance(s) over 31 class(es), 94 declaration(s); 57 '[[dep]]' row(s), 0 question(s): unlisted-dep-edge legacy -> plane busbar-llm -> busbar-plane-llm is a shipped edge w
kind-isolation	kind-isolation:test-deps	3 finding(s), 32 test edge instance(s) over 18 class(es), 32 declaration(s); 17 '[[dep]]' row(s), 0 question(s): unlisted-dep-edge cleanliness -> legacy busbar-core-admin -> busbar-a2a is a test edge
kind-isolation	kind-isolation:law0	23 finding(s) over 14 neutral crate(s): law0-rise busbar × auth 68 hit(s) against a ceiling of 46: this landing grew a neutral crate's instance vocabulary. Ceilings only fall (measured on predev f830f
kind-isolation-ship	kind-isolation:deps	11 finding(s) over 94 shipped edge(s): ship-edge kernel -> hooks busbar-kernel -> busbar-hook-ranking is 'not-allowed': the architecture grants no kernel -> hooks edge, and the ship criterion is the a
kind-isolation-ship	kind-isolation:test-deps	7 finding(s) over 32 test edge(s): ship-edge cleanliness -> legacy busbar-core-admin -> busbar-a2a is 'not-allowed': the architecture grants no cleanliness -> legacy edge, and the ship criterion is th
kind-isolation-ship	kind-isolation:law0	23 finding(s) over 14 neutral crate(s): law0-rise busbar × auth 68 hit(s) against a ceiling of 46: this landing grew a neutral crate's instance vocabulary. Ceilings only fall (measured on predev f830f
kind-isolation-ship	kind-isolation:faces	2 finding(s) over 40 crate(s): foreign-entry crates/busbar busbar is kind 'root' and implements 'Transport' 1 time(s) in shipped source — the entry face of kind 'transport'. A trait implementation is
kind-isolation-ship	kind-isolation:legacy-drain	3 finding(s): transitional-live qa/kind-isolation.toml 'busbar-a2a -> busbar-core-admin' (legacy drain: the retiring A2A engine's tests drive the admin surface that drained into the cleanliness tier)
ship-ready	ship-ready:ship-twin	'kind-isolation-ship' is not green: kind-isolation:deps (a dependency the architecture does not grant is still in the graph); kind-isolation:test-deps (a dependency the architecture does not grant is
structure-lint	structure-lint:plane-dup:unledgered	22 finding(s): PLANE-DUPLICATE (module): 'config.rs' — a2a:crates/busbar-a2a/src/a2a/config.rs decisions:crates/busbar-plane-decisions/src/config.rs voice:crates/busbar-voice/src/config.rs (the ledger

Denied because (2)

• shard 1/4: gate:kind-isolation row kind-isolation:law0: figure rose 18 -> 23
• shard 1/4: gate:kind-isolation-ship row kind-isolation:law0: figure rose 18 -> 23

Judged against base abc07fea9: 0 new red, 2 worse, 3 standing (excused).

tests passed: 24158, failed: 0. Run: https://github.com/GetBusbar/busbar/actions/runs/38019438231 . Artifact verdict-7e049173fb9f8cb3d0725e8e5bdf5e1684f67789 (failures.json, junit.xml, raw.log; 90 days).