HUB-WP-0006: record A5 packet intake and T07 alias seed + RM_SLICE_TOPICSPINE

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 356991@bnt-lap001
Assistant-Session: 5d99ea69-ed55-4a1e-8d97-f4f312db247f

workplans/HUB-WP-0006-repository-classification-navigation.md

@@ -9,7 +9,7 @@ flavor: implementation
 owner: codex
 topic_slug: custodian
 created: "2026-08-22"
-updated: "2026-10-04"
+updated: "2026-10-13"
 parent_project: prj-state-hub-retirement
 parent_workplan: STATE-WP-0079
 related:
@@ -200,6 +200,65 @@ placement/networking outside this repository. Marking the workplan `blocked`
 rather than `active` since nothing further can move here until that external
 gate closes.
 
+A5 packet intake 2026-10-13: State Hub delivered the comparison packet
+(`state-hub/docs/a5-topic-spine-comparison-packet.md`, cases
+`docs/evidence/a5-topic-spine-comparison-cases.json`, A5-C01..C10). It named two
+hub-core gaps: no alias source, and no `RM_SLICE_TOPICSPINE`. T07 closes both in
+code. The flag stays `off` everywhere, so T06 remains `wait` for the deployed
+candidate run and the switch window.
+
+## Seed legacy topic aliases and implement the A5 rollback switch
+
+```task
+id: HUB-WP-0006-T07
+status: done
+priority: high
+depends_on: []
+```
+
+Done 2026-10-13 (commit `9e4d5ba`). Not pushed or deployed. The flag has not
+been changed in any environment.
+
+- **Alias source:** `hub_core/runtime/data/legacy_topic_aliases.json`, alias set
+  `2026-10-13.1`. It holds the 16 active topics from State Hub's 2026-10-13
+  `GET /topics/?status=active` capture. Each maps to `primary_domain` =
+  `domain_slug`, with `residual_owner` `STATE-WP-0079` and `expires_at`
+  `2027-03-31T23:59:59Z`. The expiry is a conservative choice: it covers the
+  switch window plus a dual run, and it can be renewed by editing the seed and
+  bumping its version. The seed is validated against the 1.0.0
+  `legacyTopicAlias` schema and is never fetched live. Topic UUIDs are kept
+  verbatim. Three slugs with underscores (`inter_hub`, `vergabe_teilnahme`,
+  `citation_evidence_mvp`) are emitted with hyphens, because the 1.0.0 pattern
+  forbids `_`. Emitting the exact spelling needs a contract patch.
+- **Flag:** `RM_SLICE_TOPICSPINE` takes `off`, `shadow` or `on`; the default is
+  `off`.
+  - `off` leaves the output byte-for-byte unchanged (`legacy_topic_aliases: []`).
+  - `shadow` serves the aliases for comparison only.
+  - `on` declares hub-core the switched A5 read source.
+
+  Rollback is setting the flag back to `off`. The values are documented in
+  `docs/runtime.md`.
+- **Local comparison against fixtures:** see `tests/test_legacy_topic_aliases.py`.
+  - Pass: A5-C01 (16/16 aliases equal after the `_`→`-` normalisation), A5-C02
+    and the identity part of A5-C08 (each topic id resolves to exactly one alias),
+    and the hub-core half of A5-C10 (`off` withdraws the aliases).
+  - A5-C03 differs from the packet's expectation. An unknown domain returns
+    `400`, because the runtime validates the controlled vocabulary; it does not
+    return `200` with an empty list. A known domain with no repositories returns
+    `200 []`.
+  - A5-C04, C05, C06 and C07 need the deployed registry. The fixtures hold only
+    two synthetic repositories.
+  - A5-C09 has nothing to compare.
+  - The State Hub half of C10 is a legacy read.
+- **Tests:** full suite: 488 passed, 3 skipped.
+- **Still needed before T06 can run live:**
+  - deploy an image containing `9e4d5ba` and set `shadow` on the candidate only,
+    after approval;
+  - a verified candidate base URL and auth;
+  - the 154 vs 123 repository gap (out of scope here and unexplained);
+  - topic-route usage figures from the legacy meter;
+  - caller-owner switch plans.
+
 ## Acceptance
 
 - [x] Repo Manager v1.0 authority and projection contract accepted