Improve handler shape validation guidance#101
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simongdavies merged 2 commits intomainfrom May 3, 2026
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Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>
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Pull request overview
This PR improves the handler-shape validation and user guidance around register_handler by loosening parameter requirements (custom parameter names / no parameter) and providing clearer remediation messaging for common invalid handler forms (notably arrow handlers).
Changes:
- Extend JS validation to (a) treat plain
function handler(...) {}declarations as “module mode”, (b) allow handlers with custom/zero parameters, and (c) provide more targeted structure error guidance. - Add/expand test coverage for the updated validator behavior (TS-side analysis guest tests + sandbox tool execution tests).
- Update agent-facing guidance (system message + tool/help text) to reflect the supported handler shapes and common invalid patterns.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.
Show a summary per file
| File | Description |
|---|---|
| tests/sandbox-tool.test.ts | Adds execution tests for module handlers with custom parameter names and with no parameters. |
| tests/analysis-guest.test.ts | Adds validator tests for module-mode detection, allowed signatures, and improved guidance for invalid handler shapes. |
| src/code-validator/guest/runtime/src/validator.rs | Implements signature-issue detection, updates module-mode detection, and adjusts handler structure validation messaging. |
| src/agent/system-message.ts | Updates the “mandatory handler format” guidance to mention async-only-with-await, flexible params, and arrow-handler rejection. |
| src/agent/index.ts | Updates tool/help text for register_handler and handler guidance to align with the validator’s rules. |
…sistency
- Gate return-check on has_handler_function && no signature issue to
avoid misleading 'MUST return' errors on invalid handler shapes
- Expand check_handler_has_return skip logic to also skip arrow function
bodies (=> { ... }) and generator declarations (function*)
- Fix conflicting guidance in register_handler tool description: use
function handler(...) instead of function handler(event) in REQUIRED line
- Add zero-parameter form function handler() to system-message signature list
Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>
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