fix(pm): unify listWorkItems contract so backlog-manager sees Linear cards

[zbigniewsobiecki]

Summary

Backlog-manager for Linear-backed projects (e.g. llmist) saw BACKLOG as empty even when items existed (MNG-97 confirmed in backlog). The chained backlog-manager run for MNG-96/PR-571 reported:

## Pipeline Check
**Active pipeline count:** 0 (TODO: 0, IN_PROGRESS: 0, IN_REVIEW: 0)
The pipeline has capacity (0 < 1), but the BACKLOG is empty

Root cause: PMProvider.listWorkItems(containerId, filter?) had incompatible per-provider semantics for containerId:

Provider	What containerId meant	What happened with status-as-containerId
Trello	The list ID directly	✅ Works (lists ARE statuses)
JIRA	The project key	❌ JQL project = "<status name>" returned 0
Linear	The team ID	❌ listIssues({ teamId: <state-uuid> }) returned 0

The snapshot loader (contextSteps.fetchPipelineLists) called provider.listWorkItems(list.id) where list.id was a status identifier — silently returning [] for both JIRA and Linear since the day PR #1131 made buildPipelineLists populate Linear statuses.

Fix — unify the abstraction

• PMProvider.listWorkItems(containerId: string | undefined, filter?) — containerId is now optional. Each provider self-resolves the natural scope from its own config when omitted: Trello uses config.lists[filter.status], JIRA defaults to config.projectKey, Linear defaults to config.teamId. The filter.status is the CASCADE-canonical key ('backlog', 'todo', ...), mapped to the provider's native identifier internally.
• contextSteps.fetchPipelineLists — calls provider.listWorkItems(undefined, { status: list.statusKey }) for all 3 providers in one code path.
• PipelineList shape: { name, statusKey } (dropped the dead id field). Snapshot output now shows ## BACKLOG (status: backlog) instead of (list ID: <UUID>) — the agent uses CASCADE keys with move-work-item, not the underlying provider IDs.
• backlog-check.ts:isPipelineAtCapacity — collapsed Trello/JIRA dispatch into one unified path (~50 lines deleted). Now also works for Linear without code change. The per-provider knowledge survives only in isProviderMisconfigured, which preserves the conservative-fallback behaviour and uses an exhaustive switch over PMType (with assertNeverPMType in default) so a 4th provider fails the build.
• agent-execution.ts:propagateAutoLabelAfterSplitting — same simplification (~25 lines deleted).
• TrelloPMProvider constructor now requires TrelloConfig. TrelloIntegration.createProvider falls back to an empty config when getTrelloConfig returns undefined (the CLI's CredentialScopedCommand synthesizes a pm: { type: 'trello' } shell with no trello field for gadget-scope purposes; gadgets always pass containerId explicitly, so self-resolution is never exercised on that path).

Tests

• tests/unit/pm/{trello,jira,linear}-adapter.test.ts — 10 new tests for self-resolution from each provider's config + backwards-compat for explicit containerId.
• tests/unit/agents/definitions/pipelineSnapshot.test.ts — updated to assert unified call shape; updated list ID: → status: in output assertions.
• tests/unit/triggers/shared/backlog-check.test.ts — dropped the STATUS_KEY_BY_FIXTURE translation shim, rewrote 27 fixture keys to CASCADE form, added 5 Linear-specific tests, replaced unsupported-provider test with .rejects.toThrow(/Unhandled PMType/) exhaustiveness check.
• tests/helpers/factories.ts — new createMockLinearProject.
• tests/unit/triggers/agent-execution.test.ts + tests/unit/triggers/shared/agent-execution.test.ts — updated 5 assertions to use the unified call shape; replaced mockResolvedValue with per-status mockImplementation so capacity checks see empty in-flight statuses correctly.

7845 unit + 524 integration tests pass. lint+typecheck+build clean.

Out of scope

• ❌ The CLI gadget (cascade-tools pm list-work-items --containerId X) keeps its existing explicit-containerId form.
• ❌ Backfilling MNG-97 manually — once this lands, the next chained backlog-manager will see it.
• ❌ Removing the remaining double-read of provider config in isProviderMisconfigured (read here AND in adapter self-resolution). Acceptable architectural trade-off — the per-provider knowledge is correctly isolated to misconfiguration detection.

Test plan

• npm test (7845 pass)
• npm run test:integration (524 pass, ~5.5 min)
• npm run typecheck, npm run lint clean
• npm run build produces dist artifacts
• After deploy: trigger a Linear-backed chain on llmist, watch backlog-manager pick up MNG-97 and move it to TODO. Snapshot output should show ## BACKLOG (status: backlog) with MNG-97 listed.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 97.80220% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/pm/jira/adapter.ts	88.88%	1 Missing ⚠️
src/pm/trello/adapter.ts	87.50%	0 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!