fix: apply max plugin delay compensation

[ChuxiJ]

Summary

• apply plugin delay compensation using the maximum active chain latency across tracks
• exclude bypassed plugins from latency totals and sanitize live latency reports
• preserve VST3 companion latency from instance creation and later latencyInfo updates

Verification

• npx tsc --noEmit --pretty false
• npx vitest run src/services/vst3bridge/tests/PluginEngineLatency.test.ts src/services/vst3bridge/tests/VST3LatencyCompensation.test.ts src/services/vst3bridge/tests/VST3PluginAdapter.test.ts src/hooks/tests/useEffectsSync.vst3.test.ts src/store/tests/vst3Store.test.ts
• git diff --check

Closes #1783

[ChuxiJ]

Codex review completed.

Result: PASS

No actionable regressions were found in the latency propagation and compensation changes. Local verification passed:

• npx tsc --noEmit --pretty false
• npx vitest run src/services/vst3bridge/tests/PluginEngineLatency.test.ts src/services/vst3bridge/tests/VST3LatencyCompensation.test.ts src/services/vst3bridge/tests/VST3PluginAdapter.test.ts src/hooks/tests/useEffectsSync.vst3.test.ts src/store/tests/vst3Store.test.ts
• git diff --check

[Copilot]

Pull request overview

This PR updates VST3 plugin delay compensation (PDC) to align tracks using the maximum active plugin-chain latency across tracks, while also improving how VST3 latency is tracked and updated live from the companion.

Changes:

• Track and sanitize per-instance VST3 latency (latencySamples) from instantiation and subsequent latencyInfo updates.
• Compute cross-track PDC using max chain latency and apply per-track compensation (instead of delaying each track by its own latency).
• Exclude bypassed plugins from chain latency totals; add/extend unit tests around bypass and live latency updates.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/types/vst3.ts	Adds optional latencySamples to the active instance model.
src/store/vst3Store.ts	Persists initial latency on load and adds _updateLatency to apply/store live latency updates.
src/store/tests/vst3Store.test.ts	Tests initial latency capture and live latency updates to store + PluginEngine.
src/services/vst3bridge/tests/PluginEngineLatency.test.ts	Tests bypass exclusion from latency and live latency update behavior.
src/services/vst3bridge/VST3PluginAdapter.ts	Stores latency internally and exposes setLatencySamples for live updates.
src/hooks/useVST3Connection.ts	Subscribes to latencyInfo and forwards updates into the store.
src/hooks/useEffectsSync.ts	Applies max-latency-based compensation across tracks via TrackNode.setLatencyCompensation.
src/hooks/tests/useEffectsSync.vst3.test.ts	Adds coverage for cross-track max-latency compensation calculations.
src/engine/PluginEngine.ts	Excludes bypassed nodes from chain latency; adds setPluginLatency API for live updates.

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[ChuxiJ]

Addressed Copilot review feedback:

• Replaced the event-name-dependent loadPlugin flow with client.instantiate() request/response handling.
• Updated the VST3 sync fingerprint comment to include timing changes.
• Normalized chain latency aggregation to integer samples and added a regression test for fractional/invalid latency values.

Re-verified locally:

• npx tsc --noEmit --pretty false
• npx vitest run src/services/vst3bridge/tests/PluginEngineLatency.test.ts src/services/vst3bridge/tests/VST3LatencyCompensation.test.ts src/services/vst3bridge/tests/VST3PluginAdapter.test.ts src/hooks/tests/useEffectsSync.vst3.test.ts src/store/tests/vst3Store.test.ts
• git diff --check

[ChuxiJ]

Addressed second Codex review finding:

• Excluded group/bus tracks from leaf-track plugin delay compensation so child audio routed through a group bus is not delayed twice.
• Added regression coverage for an excluded group bus with plugin latency.

Re-verified locally:

• npx tsc --noEmit --pretty false
• npx vitest run src/services/vst3bridge/tests/PluginEngineLatency.test.ts src/services/vst3bridge/tests/VST3LatencyCompensation.test.ts src/services/vst3bridge/tests/VST3PluginAdapter.test.ts src/hooks/tests/useEffectsSync.vst3.test.ts src/store/tests/vst3Store.test.ts
• git diff --check

[ChuxiJ]

Addressed third Codex review finding:

• Plugin delay compensation now uses routed signal-path latency for leaf tracks.
• Child tracks include parent group-bus plugin latency in their path total.
• Group buses are still assigned 0 explicit compensation so grouped audio is not double-delayed.

Re-verified locally:

• npx tsc --noEmit --pretty false
• npx vitest run src/services/vst3bridge/tests/PluginEngineLatency.test.ts src/services/vst3bridge/tests/VST3LatencyCompensation.test.ts src/services/vst3bridge/tests/VST3PluginAdapter.test.ts src/hooks/tests/useEffectsSync.vst3.test.ts src/store/tests/vst3Store.test.ts
• git diff --check

[ChuxiJ]

Final Codex review completed after the signal-path PDC fix.

Result: PASS

No discrete, actionable regressions were identified in the diff. Type checking and targeted changed tests pass.