feat(linear): full label parity with Trello — dropdown + create-label UX

[zbigniewsobiecki]

Summary

Brings Linear label configuration to full parity with the Trello wizard. Replaces the Linear free-text label inputs with a dropdown of the team's existing labels, plus per-slot and batch "Create" buttons that provision CASCADE's default labels in one click.

This also fixes the silent bug where cascade-processing / cascade-processed / etc. were never actually applied to Linear issues: the wizard stored names, but Linear's issueUpdate.labelIds requires UUIDs — Linear silently rejected the writes and the worker's label operations no-op'd.

What's shipped

Backend

• linearClient.createLabel(teamId, name, color?) wraps Linear's issueLabelCreate GraphQL mutation, returning { id, name, color }. 6 new unit tests.
• integrationsDiscovery.createLinearLabel and createLinearLabels (batch) tRPC mutations mirror the Trello equivalents — single-label creation and batch creation with per-label error reporting.

Wizard

• LinearFieldMappingStep label UI now matches Trello:
  • Dropdown sourced from linearTeamDetails.labels (already fetched by existing discovery).
  • Values are label UUIDs, not names.
  • Per-slot "Create" button when the default isn't present yet.
  • "Create All Missing (N)" batch button at the section header.
  • Exports LINEAR_LABEL_DEFAULTS (name + hex color per slot).
• useLinearLabelCreation hook mirrors useTrelloLabelCreation — single + batch mutation, dispatches ADD_LINEAR_TEAM_LABEL and SET_LINEAR_LABEL on success.
• INITIAL_LINEAR_LABELS is now {} — the wizard populates mappings via selection or creation, not seeded names.

Adapter hardening

• LinearPMProvider.resolveLabelId validates the resolved value is UUID-shaped. If the config mapping is missing or holds a name (from a pre-existing broken configuration), addLabel / removeLabel short-circuit with a clear warn instead of silently passing a bad value to Linear.
• createWorkItem.labelIds filters out non-UUID values with the same warn.

Per-provider parity after this PR

Provider	Wizard UX	Stores	Auto-create
Trello	dropdown + Create button	UUIDs	✓
JIRA	free-text (JIRA API auto-creates on use)	names	✓ (server-side)
Linear	dropdown + Create button	UUIDs	✓ (via wizard)

Operator action required

Existing Linear-backed projects have names stored in project.linear.labels (e.g. processing: "cascade-processing"). After this PR deploys:

• Open the project's PM wizard → Label Mappings step.
• Dropdowns will show empty because the saved name no longer matches any option value.
• Either pick existing labels from the dropdown, or click Create All Missing to provision CASCADE's defaults in one click.

Going forward the wizard persists UUIDs and cascade-processing will actually attach to issues.

Tests

• linearClient.createLabel — 6 new tests (returns shape, omits color when absent, passes input, success=false, GraphQL errors, HTTP errors)
• LinearPMProvider — updated fixture to UUID-shaped values; new test: "skips the API call and warns when the value is neither a mapped slot nor a UUID"
• LinearFieldMappingStep — new "label slots" describe: dropdown uses UUIDs not names, Create buttons show/hide correctly based on existing labels, persisted mappings reflect as selected option values
• Full test suite: 7687 passing, lint + typecheck clean

Files changed

• src/linear/client.ts — createLabel method
• src/api/routers/integrationsDiscovery.ts — createLinearLabel + createLinearLabels endpoints
• src/pm/linear/adapter.ts — resolveLabelId validation helper wired into createWorkItem / addLabel / removeLabel
• web/src/components/projects/pm-wizard-state.ts — ADD_LINEAR_TEAM_LABEL action + reducer; empty initial labels
• web/src/components/projects/pm-wizard-linear-steps.tsx — new LinearFieldMappingStep label UI + LINEAR_LABEL_DEFAULTS export
• web/src/components/projects/pm-wizard-hooks.ts — useLinearLabelCreation
• web/src/components/projects/pm-wizard.tsx — wire handlers into LinearFieldMappingStep

Test plan

• npm run lint, npm run typecheck, full npm test clean locally (7687 tests)
• After deploy-dev: re-open the dev project's PM wizard, click "Create All Missing" on the Label Mappings step. Confirm 5 labels are created in Linear with the expected names + colors, and the dropdowns show them as selected.
• Trigger a Linear status transition that fires an agent. Confirm the agent's cascade-processing label is actually applied to the issue in Linear (visible in the Linear UI).

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 61.16505% with 40 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/api/routers/integrationsDiscovery.ts	42.18%	37 Missing ⚠️
src/pm/linear/adapter.ts	85.71%	3 Missing ⚠️

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