feat(orchestrator): add LinearIssues variant to TriggerConfig

[geoffjay]

Summary

• Adds LinearIssues variant to TriggerConfig with five optional filter fields: team_key, project, status, labels, assignee
• trigger_type() returns "linear_issues" (snake_case, consistent with all existing variants)
• is_implemented() converted from matches! to an explicit match — returns false for LinearIssues until LinearIssueSource is implemented in Implement LinearIssueSource task source #475
• Explicit LinearIssues arm added to the API validation match in scheduler/api.rs (no field-level validation yet since all fields are optional)
• display_workflow() in the CLI prints each non-empty Linear field

Test plan

• cargo build -p orchestrator -p cli — clean, no warnings
• cargo clippy -p orchestrator -p cli — clean
• 4 new unit tests: trigger_type, full serde deserialization, minimal/default serde, and roundtrip serialization
• Existing 234 orchestrator tests all pass (3 pre-existing macOS sandbox failures in client::tests unrelated to this change)

Closes #473

🤖 Generated with Claude Code

[geoffjay]

Good foundational change for the Linear integration epic. The type definition is clean, serde defaults are correct, and the explicit match in is_implemented() is a clear improvement over the old matches! macro — the compiler will now catch any future unhandled variant at compile time.

Two issues worth addressing before or alongside issue #475:

1. Stale error message in api.rs (minor, pre-existing but now misleading)

The rejection message for unimplemented trigger types reads:

"Currently supported: github_issues, github_pull_requests, cron, delay"

That list was already wrong (missing agent_lifecycle, dispatch_result, webhook, manual), but it becomes actively misleading now that linear_issues will trigger it. A caller who POSTs a linear_issues workflow will receive an error claiming only those four types are supported. The message should either enumerate all currently implemented types or be reworded generically (e.g. "check the documentation for currently supported trigger types").

2. Test placement (maintainability)

The four new tests (test_trigger_config_linear_issues_*) are in crates/cli/src/commands/orchestrator.rs but they test pure type behaviour — serde round-trips, trigger_type(), and is_implemented() — with no CLI dependency at all. They belong in crates/orchestrator/src/scheduler/types.rs alongside the existing test_trigger_config_is_implemented test. Having type-level tests in the CLI crate makes them harder to find and means a cargo test -p orchestrator run will miss them.

---

Everything else looks correct: no unwrap() on fallible paths, all fields properly #[serde(default)]-annotated, is_one_shot() correctly returns false for LinearIssues via the existing matches!(self, Delay {..}), and the display_workflow arm handles all optional fields safely with if let Some / !is_empty() guards.

[codecov]

Codecov Report

❌ Patch coverage is 20.00000% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 55.36%. Comparing base (d5e7cc7) to head (c399df6).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/cli/src/commands/orchestrator.rs	0.00%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #482      +/-   ##
==========================================
- Coverage   55.39%   55.36%   -0.03%     
==========================================
  Files         126      126              
  Lines       13518    13533      +15     
==========================================
+ Hits         7488     7493       +5     
- Misses       6030     6040      +10     

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