daemon.spec: stub bridge-daemon instance resolver (ps) — unit tests env-dependent on host Claude.app

Problem

ai/daemons/bridge/daemon.mjs deliverDigest() resolves the target instance pid via getInstancePid / getDefaultInstancePid (which shell out to real ps). test/playwright/unit/ai/daemons/bridge/daemon.spec.mjs does not stub that resolver, so the osascript the daemon builds depends on the host machine's running processes:

• On CI (no Claude.app running): getDefaultInstancePid({appName:'Claude'}) returns null → the daemon uses the tell application "Claude" to activate path → tests asserting the activate line pass.
• On an agent-harness machine (Claude Desktop running — i.e. every agent's machine, especially with the 2-instance bring-up): getDefaultInstancePid resolves a real pid → the daemon takes the set frontmost of (first process whose unix id is <pid>) path → there is no activate token → tests like daemon.spec.mjs:704 ("Claude default focus seed …") fail at expect(activateIndex).toBeGreaterThan(-1) (activateIndex = -1).

So these unit tests pass on CI but fail locally on harness machines — a determinism / CI-vs-host-parity hazard (a unit test must not depend on the host's live process list).

Repro

Run with Claude Desktop running on the host:

npm run test-unit -- test/playwright/unit/ai/daemons/bridge/daemon.spec.mjs

→ the default-instance / activate-path tests fail (activateIndex === -1); the rest pass.

Fix

Stub the instance resolver in daemon.spec setup so resolution is deterministic regardless of host state:

• Default-instance / activate-path tests → stub getDefaultInstancePid (and getInstancePid) to return null.
• Instance-addressed tests → stub to return a fixed pid.

Inject via the existing seam (instanceResolver.mjs exports getInstancePid/getDefaultInstancePid; or thread an injectable exec as the resolver functions already support for testing). Audit all deliverDigest-exercising tests for the same host dependency.

Origin / Scope

• Surfaced while reviewing PR #12424 (#10422 frontmost guard) on a harness machine with live Claude instances.
• The real-ps dependency in deliverDigest was introduced by #12399 / #12407 (instance-addressable wake routing); the spec was not updated to stub it. Not a #12424 defect — #12424's new guard test merely inherits the same host dependency.
• Test-only change. No runtime behavior change.