chore(workplan): stub RREG-WP-0012 activity-core context API

Workplan for stabilising the GET /repos/{slug}/scope endpoint as a
formal contract for activity-core's RepoScopingContextResolver. Covers
schema definition, scope_md_exists field, and provider-side contract test.

Hub workstream: 83a43ab6-d566-41e0-afd7-f2833812564f

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

workplans/RREG-WP-0012-activity-core-context-api.md

@@ -0,0 +1,152 @@
+---
+id: RREG-WP-0012
+type: workplan
+domain: custodian
+repo: repo-scoping
+status: active
+state_hub_workstream_id: 83a43ab6-d566-41e0-afd7-f2833812564f
+tasks:
+  - id: T01
+    title: Define context query response schema for activity-core
+    state_hub_task_id: 83482f1d-4f44-440d-a27f-0c375786b87f
+    status: todo
+  - id: T02
+    title: Verify/implement GET /repos/{slug}/scope endpoint
+    state_hub_task_id: 75f6123a-2703-42ec-9564-dd665e16c5ef
+    status: todo
+  - id: T03
+    title: Add scope_md_exists boolean to scope response
+    state_hub_task_id: cb0b17f4-30c4-4d68-b2ff-9a3fa9ef73a3
+    status: todo
+  - id: T04
+    title: Write integration test for activity-core repo-scoping adapter
+    state_hub_task_id: f70c1c58-b23f-4b61-adca-a02644b6ee7e
+    status: todo
+created: "2026-05-14"
+---
+
+# RREG-WP-0012: Activity-Core Context API
+
+## Purpose
+
+activity-core's `RunActivityWorkflow` resolves context before evaluating rules
+and instructions. One of its context sources is repo-scoping: given a repo slug,
+it queries repo-scoping for the repo's capability profile (tags, capabilities,
+whether a SCOPE.md exists, etc.).
+
+This workplan ensures repo-scoping exposes a stable, documented context API
+endpoint that activity-core can call reliably. It is a **contract workplan** —
+the goal is a stable interface, not new functionality.
+
+## Context
+
+- **activity-core WP-0003** (in progress): implements `RepoScopingContextResolver`
+  in `src/activity_core/context_resolvers/repo_scoping.py` which calls
+  `GET /repos/{slug}/scope` on the repo-scoping API.
+- **repo-scoping** already has a scope API; the question is whether it returns
+  the exact fields activity-core needs, and whether those fields are stable.
+
+See: `docs/adr/adr-001-event-bridge-architecture.md` in activity-core, section
+on context resolution adapters.
+
+## Scope
+
+**In scope:**
+- Documenting and stabilizing the `/repos/{slug}/scope` endpoint response schema
+- Adding `scope_md_exists` if not present
+- Contract/integration test
+
+**Out of scope:**
+- Dynamic operational state (that is the state hub's domain, not repo-scoping's)
+- NATS-based context queries (REST only for now)
+- Any new scope analysis features
+
+## Contract
+
+The endpoint `GET /repos/{slug}/scope` must return:
+
+```json
+{
+  "repo_slug": "string",
+  "capabilities": ["string"],
+  "tags": ["string"],
+  "scope_md_exists": true,
+  "scope_summary": "string or null"
+}
+```
+
+| Field | Type | Required | Notes |
+|---|---|---|---|
+| `repo_slug` | string | yes | URL-safe identifier |
+| `capabilities` | string[] | yes | Declared capability types |
+| `tags` | string[] | yes | Free-form classification tags |
+| `scope_md_exists` | boolean | yes | True if SCOPE.md present in repo root |
+| `scope_summary` | string or null | no | First paragraph of SCOPE.md if present |
+
+This schema is the contract. Changes must be versioned and communicated to the
+activity-core agent before deployment.
+
+## Tasks
+
+### T01 — Define context query response schema for activity-core
+
+Write a JSON Schema file (`docs/schemas/repo-scope-context-response.json`) that
+formalizes the response shape above. Include field descriptions and examples.
+This becomes the machine-readable contract between repo-scoping and activity-core.
+
+### T02 — Verify/implement GET /repos/{slug}/scope endpoint
+
+Check the existing API for `GET /repos/{slug}/scope`. Verify it returns all
+required fields. If missing fields, implement them. If the endpoint does not
+exist, implement it.
+
+The endpoint is called by activity-core's `RepoScopingContextResolver` and
+must be stable — no breaking changes without coordinating with activity-core.
+
+### T03 — Add scope_md_exists boolean to scope response
+
+Ensure `scope_md_exists` is present and accurate: `true` if a `SCOPE.md` file
+exists in the repo's root directory on the default branch, `false` otherwise.
+
+This field is used by activity-core rules to decide whether to emit a
+generate-SCOPE.md task for a repo.
+
+### T04 — Write integration test for activity-core repo-scoping adapter
+
+Write a contract test that:
+1. Calls `GET /repos/{slug}/scope` with a known test repo slug
+2. Asserts all required fields are present
+3. Asserts types match the schema (scope_md_exists is bool, capabilities is list, etc.)
+
+This test lives in repo-scoping as the provider-side contract test. It should
+run in CI so contract drift is caught before it breaks activity-core.
+
+**Test file**: `tests/test_scope_context_api.py` (or alongside existing API tests)
+
+## Build Order
+
+```
+T01 (schema) → T02 (implement) → T03 (add field) → T04 (test)
+```
+
+## Completion Criteria
+
+1. `GET /repos/{slug}/scope` returns all five required fields
+2. `scope_md_exists` is accurate for at least three test repos
+3. JSON Schema file committed to `docs/schemas/`
+4. Contract test passes in CI
+5. activity-core agent confirmed the `RepoScopingContextResolver` integration works
+
+## Notes
+
+- The local agent implementing this should coordinate with the activity-core agent
+  to confirm the exact field names and types before implementing T02.
+- Do **not** add dynamic operational state to this endpoint (e.g., last_commit_at,
+  open_issues_count) — that belongs to the state hub context adapter, not repo-scoping.
+- `scope_summary` is optional (null OK) — do not block on extracting it if the
+  SCOPE.md parsing is complex.
+
+## Change History
+
+- v0.1 (2026-05-14): Stub created by activity-core agent during WP-0003 planning.
+  Local agent to flesh out and implement.