contrib: FR for update_workstream MCP tool

Missing tool discovered during offline-inbox drain — repo_goal_id on
workstream bf40b47e is null in DB but correctly set in the workplan file.
No MCP path to fix this without a direct API call.

Contribution id: 0450a858-bccc-4cbf-8052-38c1654aa005

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

contrib/feature-requests/fr-2026-03-09--threephoenix--state-hub--update-workstream-tool.md

@@ -0,0 +1,56 @@
+---
+type: feature-request
+id: fr-2026-03-09--threephoenix--state-hub--update-workstream-tool
+target_org: threephoenix
+target_repo: state-hub
+status: draft
+created: "2026-03-09"
+source_repo: railiance-hosts
+related_workstream_id: bf40b47e-be5b-4930-a7d2-362e76b943bb
+---
+
+# FR: `update_workstream` MCP Tool
+
+## Problem
+
+The MCP server exposes `update_workstream_status` (status changes only) but no
+general `update_workstream` tool. This means fields like `repo_goal_id`, `title`,
+`description`, `owner`, and `due_date` cannot be updated via MCP once a workstream
+is created.
+
+This was discovered during offline-inbox drain: the workplan file `RAIL-HO-WP-0001`
+correctly references `repo_goal_id: 9e835b82-acca-493a-943f-2553ffe0bf54`, but the
+DB workstream (`bf40b47e`) has `repo_goal_id: null` because the field was not set
+at creation time. There is no tool to fix this without a direct API call.
+
+The `goal_guidance` section of `get_domain_summary()` then surfaces a false
+`needs_workplan` warning for the linked goal, because the DB record is incomplete.
+
+## Proposed Solution
+
+Add an `update_workstream` MCP tool:
+
+```python
+update_workstream(
+    workstream_id: str,
+    title: str | None = None,
+    description: str | None = None,
+    owner: str | None = None,
+    due_date: str | None = None,       # ISO date
+    repo_goal_id: str | None = None,   # UUID
+    repo_id: str | None = None,        # UUID
+)
+```
+
+Semantics: patch — only provided fields are updated. Returns the updated workstream.
+
+## Acceptance Criteria
+
+- Claude can set `repo_goal_id` on an existing workstream
+- Partial updates (only provided fields change, others unchanged)
+- `get_domain_summary()` goal_guidance reflects the updated linkage after the call
+
+## Priority
+
+Medium. Workaround is a direct API call, but this breaks the MCP-only workflow
+and leaves audit gaps when agents operate without direct API access.