fix(acp): add tests asserting cwd and mcpServers are always passed to session/load (#1593)

[theslava]

Linked issue

Closes #1593

Type of change

• Bug fix
• New feature (with prior issue + design alignment)
• Refactor / code improvement
• Docs

What does this PR do

Adds unit tests in acp-agent.test.ts that verify initializeResumedSession() always calls loadSession and unstable_resumeSession with { sessionId, cwd, mcpServers } — even when mcpServers is an empty array. Some strict ACP providers (e.g., Devin CLI) return "Invalid params" if any of these fields are omitted.

Also adds a docstring above initializeResumedSession() documenting this requirement so future refactors don't accidentally drop params.

How did you verify it

• npx vitest run packages/server/src/server/agent/providers/acp-agent.test.ts --bail=1 — 59 tests passed
• npm run typecheck — passed
• npm run lint — passed
• npm run format — ran

Risk surface

Tests only. No behavioral change — the existing code already passes all three params. This guards against a future refactor that might accidentally drop cwd or mcpServers.

Checklist

• One focused change. Unrelated cleanups split out.
• npm run typecheck passes
• npm run lint passes
• npm run format ran (Biome)
• UI changes include screenshots or video for every affected platform (N/A: no UI changes)
• Tests added or updated where it makes sense

[greptile-apps]

Greptile Summary

This PR adds regression tests and a docstring to guard the invariant that initializeResumedSession() always passes cwd and mcpServers (even as an empty array) to both loadSession and unstable_resumeSession — a hard requirement for strict ACP providers such as Devin CLI that return "Invalid params" when these fields are absent. No behavioral changes are introduced.

• A shared makeTestSession factory eliminates the per-test subclass duplication flagged in the previous review round, and handle is now passed via the typed constructor rather than a private-field cast.
• Three focused tests cover: loadSession with supportsMcpServers: true, loadSession with supportsMcpServers: false (where acpMcpServers() short-circuits to []), and the unstable_resumeSession branch — all asserting the full { sessionId, cwd, mcpServers } shape.
• A JSDoc comment above initializeResumedSession documents the constraint so future refactors cannot accidentally drop either field.

Confidence Score: 5/5

Safe to merge — purely additive tests and a docstring, zero production logic change.

All three tests exercise real code paths through initializeResumedSession, the shared factory is clean, and the docstring accurately describes the existing behavior. The PR addresses the two findings from the previous review round.

No files require special attention.

Important Files Changed

Filename	Overview
packages/server/src/server/agent/providers/acp-agent.test.ts	Adds a new describe block with three regression tests for initializeResumedSession, using a clean shared makeTestSession factory; addresses previous review comments about private-field casts and copy-paste duplication.
packages/server/src/server/agent/providers/acp-agent.ts	Adds a JSDoc warning above initializeResumedSession documenting the ACP invariant that cwd and mcpServers must always be included in session/load calls; no behavioral change.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["initializeResumedSession()"] --> B{agentCapabilities\n.loadSession?}
    B -- yes --> C["connection.loadSession({\n  sessionId,\n  cwd, mcpServers\n})"]
    B -- no --> D{sessionCapabilities\n.resume?}
    D -- yes --> E["connection.unstable_resumeSession({\n  sessionId,\n  cwd, mcpServers\n})"]
    D -- no --> F["throw: provider does\nnot support resume"]
    C --> G["applySessionState()"]
    E --> G

    subgraph "acpMcpServers()"
        H{this.capabilities\n.supportsMcpServers?}
        H -- yes --> I["normalizeMcpServers(config.mcpServers)"]
        H -- no --> J["[] always returned"]
    end

    C -.->|calls| H
    E -.->|calls| H

Loading

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flowchart TD
    A["initializeResumedSession()"] --> B{agentCapabilities\n.loadSession?}
    B -- yes --> C["connection.loadSession({\n  sessionId,\n  cwd, mcpServers\n})"]
    B -- no --> D{sessionCapabilities\n.resume?}
    D -- yes --> E["connection.unstable_resumeSession({\n  sessionId,\n  cwd, mcpServers\n})"]
    D -- no --> F["throw: provider does\nnot support resume"]
    C --> G["applySessionState()"]
    E --> G

    subgraph "acpMcpServers()"
        H{this.capabilities\n.supportsMcpServers?}
        H -- yes --> I["normalizeMcpServers(config.mcpServers)"]
        H -- no --> J["[] always returned"]
    end

    C -.->|calls| H
    E -.->|calls| H

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_{Reviews (11): Last reviewed commit: "fix(tests): ensure ACP agent session loa..." | Re-trigger Greptile}

[theslava]

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