fix(core): fall back to empty on malformed agents.json shape

[soroush5]

Closes #29207.

A corrupt agents.json (valid JSON, wrong shape — null, scalar, or array, from an interrupted save, full disk, sync conflict, or hand edit) crashed isAcknowledged/acknowledge with a raw TypeError, or silently dropped the acknowledgment (array shape). load now validates the parsed shape with a type guard and falls back to {} with a logged error, like every other load failure already does.

How to test:

1. Write null into ~/.gemini/acknowledgments/agents.json and trigger an agent acknowledgment check — no throw, treated as not-acknowledged.
2. Run npx vitest run src/agents/acknowledgedAgents.test.ts in packages/core — all 8 pass, including 4 new regression cases (null/42/"str"/[]; the first three fail without the fix).

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a potential crash in the agent acknowledgment service caused by corrupted or malformed agents.json files. By introducing structural validation during the loading process, the application now safely handles unexpected data shapes by falling back to a default empty state instead of propagating errors to the rest of the system.

Highlights

• Robustness Improvement: Added a type guard to validate the structure of the agents.json file during load, preventing crashes caused by malformed JSON shapes.
• Error Handling: Implemented a fallback mechanism that resets the acknowledgedAgents state to an empty object and logs an error when the file content does not match the expected map structure.
• Regression Testing: Added new test cases to verify that various malformed JSON inputs (null, scalars, arrays) are handled gracefully without throwing exceptions.

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[github-actions]

📊 PR Size: size/M

• Lines changed: 58
• Additions: +56
• Deletions: -2
• Files changed: 2

[gemini-code-assist]

Code Review

This pull request introduces safe JSON parsing for the acknowledged agents file, falling back to an empty object if the parsed JSON has an unexpected shape, and adds corresponding unit tests. The review feedback correctly identifies that the new isAcknowledgedAgentsMap type guard only performs a shallow check, which could still lead to runtime crashes if nested values are primitives. The reviewer suggests a more robust type guard implementation and additional test cases to cover these nested malformed shapes.

[gemini-code-assist]

The type guard isAcknowledgedAgentsMap only performs a shallow check on the top-level value. If the JSON is an object but contains non-object values (e.g., {"/project": "string"}), isAcknowledgedAgentsMap will return true. This will cause acknowledge to crash with a TypeError when trying to set a property on a primitive string (e.g., TypeError: Cannot create property 'Agent' on string).

To prevent this, the type guard should also verify that all values within the map are non-null, non-array objects.

function isAcknowledgedAgentsMap(
  value: unknown,
): value is AcknowledgedAgentsMap {
  if (!value || typeof value !== 'object' || Array.isArray(value)) {
    return false;
  }
  return Object.values(value).every(
    (val) => !!val && typeof val === 'object' && !Array.isArray(val),
  );
}

[soroush5]

You're right — I reproduced it: {"/project": "str"} passes the old guard and then acknowledge() throws TypeError: Cannot create property 'Agent' on string. Fixed by requiring every project entry to be a non-null, non-array object (falls back to empty otherwise), plus regression tests for the nested shapes. Pushed in b8cd71b — 12/12 green.

[gemini-code-assist]

Add test cases for nested malformed shapes (such as an object containing a string or null value) to ensure the improved type guard prevents crashes on these shapes as well.

Suggested change

	it.each(['null', '42', '"str"', '[]'])(
	it.each(['null', '42', '"str"', '[]', '{"/project": "str"}', '{"/project": null}'])(

[soroush5]

Done — added {"/project": "str"}, 42, null and [] nested cases to the shape test. Without the guard fix, the truthy-primitive ones fail; with it, all 12 pass.