cold-start: split regression execution into executor module

[x0ba]

Stack Context

This stack reduces Vercel cold-start time by shrinking the shared SvelteKit server boot path and isolating heavy agent/GitHub dependencies.

Why?

regression/runs.ts statically imported the agent runner, so webhook and regression CRUD routes bundled Playwright even when no agent work ran. Execution moves to executor.ts with dynamic agent-runner imports when a case actually starts.

Test plan

• Trigger a regression suite run from the dashboard
• Confirm GitHub webhook-triggered regression runs still schedule and execute

[vercel]

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Project	Deployment	Actions	Updated (UTC)
flightlog	Ready	Preview, Comment	May 28, 2026 4:51pm

[x0ba]

• cold-start: tune Sentry sampling and Vercel function limits #45
• cold-start: split Neon and pg database drivers #44
• cold-start: lazy-load agent runner heavy dependencies #43
• cold-start: split regression execution into executor module #42 👈 (View in Graphite)
• cold-start: decouple webhook registration from server hook #41
• staging

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[greptile-apps]

Greptile Summary

This PR refactors regression execution by extracting scheduleRegressionRun and executeRegressionRun from runs.ts into a new executor.ts module, dynamically importing createAgentRun/maybeStartAgentRun (the Playwright-heavy path) only when a case actually starts. Both webhooks.ts and the suite-runs API route now import scheduleRegressionRun from executor instead of runs.

• Bundle improvement: createAgentRun and maybeStartAgentRun are now dynamic imports inside executeRegressionCase, so webhook and CRUD routes no longer pull Playwright into their static bundle.
• updateRegressionCheckRun (GitHub) was already a dynamic import in the old code and remains so.
• evaluateRun and findRun remain as static imports in executor.ts; since both webhooks.ts and +server.ts now statically import executor, these modules are still bundled on those routes — the refactor is a meaningful but partial cold-start win.

Confidence Score: 5/5

Safe to merge — the change is a clean mechanical extraction with no logic modifications.

The extraction faithfully mirrors the old logic from runs.ts into executor.ts without altering any business rules. The dynamic imports for createAgentRun and maybeStartAgentRun are the only behavioural change and they improve, not regress, the situation. The concerns previously raised (in-memory dedup across serverless instances, remaining static imports of evaluateRun/findRun) were flagged in earlier review rounds and are not introduced by this PR.

No files require special attention; executor.ts is the only new file and its logic is a direct lift from the prior runs.ts.

Important Files Changed

Filename	Overview
src/lib/server/regression/executor.ts	New module extracting scheduleRegressionRun/executeRegressionRun from runs.ts; correctly dynamic-imports agent-runner and github/checks, but still statically imports evaluateRun and findRun (noted in prior review).
src/lib/server/regression/runs.ts	Execution logic removed cleanly; remaining static imports of evaluateRun and findRun are legitimately used by completeRegressionCaseRun.
src/lib/server/github/webhooks.ts	Import of scheduleRegressionRun moved from runs to executor; no logic changes.
src/routes/api/regression/suites/[id]/runs/+server.ts	Import of scheduleRegressionRun moved from runs to executor; no logic changes.

Sequence Diagram

sequenceDiagram
    participant WH as webhooks.ts
    participant API as +server.ts (POST)
    participant Runs as regression/runs.ts
    participant Exec as regression/executor.ts
    participant DB as Database
    participant Agent as agent-runner/service (dynamic)
    participant GH as github/checks (dynamic)

    WH->>Runs: createRegressionRunForRepository()
    Runs->>DB: insert regressionRun + caseRuns
    Runs-->>WH: "{ regressionRun, suite }"
    WH->>Exec: scheduleRegressionRun(id)

    API->>Runs: createRegressionRun()
    Runs->>DB: insert regressionRun + caseRuns
    Runs-->>API: regressionRun
    API->>Exec: scheduleRegressionRun(id)
    API-->>API: return 201 (fire-and-forget)

    Note over Exec: void executeRegressionRun() async
    Exec->>DB: fetch regressionRun + caseRuns
    Exec->>DB: "set status = 'running'"
    loop For each pending caseRun
        Exec->>DB: "set caseRun status = 'running'"
        Exec->>Agent: await import() createAgentRun + maybeStartAgentRun
        Exec->>Exec: waitForRunCompletion (poll 2s, max 10min)
        Exec->>Exec: evaluateRun() [static import]
        Exec->>DB: update caseRun (success/failed)
        Exec->>GH: await import() updateRegressionCheckRun
    end
    Exec->>DB: aggregateSuiteResult update regressionRun
    Exec->>GH: updateRegressionCheckRun (final)

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_{Reviews (2): Last reviewed commit: "Move regression run execution into a ded..." | Re-trigger Greptile}

[x0ba]

Merge activity

• May 28, 4:49 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• May 28, 4:51 PM UTC: Graphite rebased this pull request as part of a merge.
• May 28, 4:51 PM UTC: @x0ba merged this pull request with Graphite.