test: make session resume E2E retries reliable

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📝 Summary

The shutdown resume E2E test could connect to the shared edit server even though its fixture configured a dedicated port. Failed attempts also left resumable sessions behind, while page-wide text assertions raced with the restored form DOM.

This routes explicitly ported edit fixtures to their dedicated server and makes the resume test establish clean retry state before asserting exact output within the resumed cell. This keeps the test focused on session restoration and prevents stale sessions or duplicate locators from affecting retries.

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✅ Merge Checklist

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• Tests have been added for the changes made.

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview	Aug 19, 2026 6:59am

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[cubic-dev-ai]

All reported issues were addressed across 2 files

Architecture diagram

sequenceDiagram
    participant Test as Playwright Test
    participant Config as playwright.config.ts
    participant App as Marimo App Server
    participant Page as Browser Page
    participant Kernel as Python Kernel

    Note over Test,Config: Test Setup - Resolve App URL
    Test->>Config: getAppUrl("shutdown.py")
    Config->>Config: Look up server options

    alt Edit command with dedicated port configured
        Config->>Config: Use dedicated port URL
        Config-->>Test: Return http://localhost:<dedicated-port>
    else Edit command without dedicated port
        Config->>Config: Use shared EDIT_PORT with ?file= query param
        Config-->>Test: Return shared port URL
    end

    Note over Test,Page: Session Resume Flow
    Test->>Page: Navigate to app URL
    Test->>Page: maybeRestartKernel()
    Page->>Kernel: Restart kernel if needed (clean state)

    Page->>Kernel: Execute shutdown.py
    Kernel-->>Page: Render form with initial output 'None'

    Test->>Page: Wait for "'None'" text visible
    Test->>Page: Fill form textbox with "12345"
    Page->>Kernel: Submit form via button click
    Kernel-->>Page: Process form data, render output

    alt Output rendering
        Page-->>Test: Show "'12345'" in second cell (exact match)
        Page-->>Test: Show "54321" in second cell (exact match)
    end

    Test->>Page: Reload page
    Page->>Kernel: Reconnect to existing session (resume)
    Kernel-->>Page: Restore form state and output cells

    Test->>Page: Wait for "You have reconnected to an existing session." visible

    alt Session data preserved after reload
        Page->>Kernel: Query resumed session state
        Kernel-->>Page: Return restored values
        Page-->>Test: Show "'12345'" in second cell (exact match)
        Page-->>Test: Show "54321" in second cell (exact match)
    end

    Test->>Test: Take screenshot for evidence

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Coverage Report for ./frontend

Status	Category	Percentage	Covered / Total
🔵	Lines	78.75%	81907 / 104006
🔵	Statements	78.75%	81907 / 104006
🔵	Functions	71.66%	703 / 981
🔵	Branches	79.36%	4931 / 6213

File Coverage

No changed files found.

Generated in workflow #20592 for commit e125382 by the Vitest Coverage Report Action

[Copilot]

Pull request overview

This PR improves Playwright E2E reliability for the “shutdown session resume” scenario by ensuring explicitly ported edit-mode fixtures connect to their dedicated server, and by tightening the resume test’s setup/assertions to avoid stale session state and DOM races.

Changes:

• Update getAppUrl to route edit fixtures with an explicit port directly to that server (instead of the shared edit server).
• Make the shutdown “resume session” test reset retry state via maybeRestartKernel and assert resumed output more precisely within the target cell.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
frontend/playwright.config.ts	Routes explicitly ported edit apps to their dedicated server URL to avoid cross-test session leakage.
frontend/e2e-tests/shutdown.spec.ts	Stabilizes the resume-session E2E flow by restarting on resumed sessions and scoping assertions to the resumed cell.

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