Sub 2 Phase 1b — MCP exposure of 5-axis REM observability primitive + doc scaffold

Parent context

Epic #12065 Sub 2 #12068 — Phase 1b follow-up to PR #12081 (Phase 1a, APPROVED, awaiting human merge). Phase 1a shipped 5 axis-count helpers across ChromaManager + GraphService + TopologyInferenceEngine. Phase 1b exposes those helpers via Memory Core MCP for operator-facing queryability + lands the learn/agentos/rem-state-model.md doc scaffold.

Dependency

BLOCKED-ON: PR #12081 merge (Phase 1a helpers must exist on origin/dev before MCP exposure can import them).

Contract Ledger

Per ticket-intake-workflow.md §7 — documented upfront per ticket-author discipline.

MCP tool surface

OpenAPI delta

Doc scaffold

Acceptance Criteria

• AC1: MCP exposure shipped — either new get_rem_pipeline_state tool OR manage_database action extension (operator/lead picks shape; both satisfy AC1)
• AC2: Returned envelope contains all 5 axes: undigested, digested, sessionNodes, topologyConflicts, plus optional per-session entityCount keyed on sessionId parameter
• AC3: Doc scaffold at learn/agentos/rem-state-model.md covers the 4 content rows above; cross-references PR #12081 helper JSDocs + PR #12077 Sub 1 forensics runbook
• AC4: Unit test for the MCP handler (mocked helpers + response shape assertion); integration test optional pending Sub 2 Phase 2 state model availability
• AC5: OpenAPI passes McpServerToolLimits validation (≤ 1024 char description per mcp-tool-description-budget.md)
• AC6: PR body includes Phase 1b → Phase 2 sequencing note (Phase 2 absorbs the per-cycle JSONL state model + wall-clock + cadence-overflow detection — see #12068 comment 4552584285)

Avoided Traps

• ❌ Don't ship Phase 1b BEFORE Phase 1a (#12081) merges — Phase 1b imports the 5 helpers Phase 1a adds
• ❌ Don't bundle Phase 2 scope (JSONL state model + wall-clock + cadence-overflow detection) — that's a separate ticket (TBD-filed-shortly) with its own AC surface
• ❌ Don't extend the helpers' return shape in this phase — helpers stay verbatim from Phase 1a; MCP layer is the projection/composition surface

Related

• Epic #12065
• Sub 2 ticket #12068
• PR #12081 (Phase 1a, dependency)
• PR #12077 Sub 1 forensics runbook (cross-references in doc scaffold)
• Sub 2 Phase 2 follow-up ticket #12088 (per-cycle JSONL state model + wall-clock + cadence-overflow detection scope)