Cut the MCP tool surface down from 37 tools #256

Result (deployed 2026-09-16)

37 tools, 25,852 characters → 27 tools, 19,020 characters: 26% less context in every agent session. McpDiscoveryTests.ToolListStaysWithinItsContextBudget pins 27 / 19,020 and prints per-tool sizes.

Commits: 2bb5bd4 budget test, 334c5f3 step 1, 5612bad step 2, 8dba19a docs.

Step 1 — merges (37 → 32)

• memory_store absorbs memory_update (number + baseRevisionId) and memory_store_many (memories + idempotencyKey); mixed forms are refused.
• task_patch replaces task_update. Found on the way: task_patch rejected resending the current assignee when that agent had been revoked; the service now treats an unchanged assignee as no assignment.
• proposal_get without proposalId lists.
• relation_backfill removed from the agent surface; the reconciliation stays in RelationService.

Step 2 — kind-agnostic items (32 → 27)

• item_get replaces item_resolve, task_get, project_memory_get and project_instructions_get (ref=instructions). Payloads unchanged, kind first; instructions carry mandatory: true, nothing else does (groundwork for #259).
• item_history replaces task_history; memories and instructions return revisions.
• item_archive (restore flag) replaces memory_archive and memory_restore.
• item_delete replaces memory_delete and task_delete and only requests privacy deletion.

Deviation: item_search was not introduced. Tasks are not searchable today, and renaming memory_search would promise a search that does not exist. Revisit with #273.

All 28 projects had empty stored instructions, so no stored guidance referenced removed tools. Connected clients must reload their MCP connection to see the new list.

Open options (separate decisions)

• item_get also accepts an id, removing memory_get (−1)
• system_memory as an MCP resource (−1; uneven client support)
• one review queue for proposals and privacy deletion requests: review_list, review_decide (−3)
• project_instructions_update folds into the document write path once #269 exists (−1)
• tighten memory_store (2,814 characters, the largest entry)