[Agent] Fix variable.undefined PHPStan error on Toolbox::execute()

[peter-si]

Q	A
Branch?	main
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	-
License	MIT

Summary

Toolbox::execute() trips PHPStan's flow analysis with:

Variable $sourceCollection might not be defined.
src/Toolbox/Toolbox.php:110

The variable is assigned inside an if ($tool instanceof HasSourcesInterface) branch on line 104, then read back via a ternary using the same instanceof check on line 110. The code is safe at runtime — PHP only evaluates the variable when the ternary condition is true — but PHPStan can't infer this control-flow correlation, so the analysis fails.

Fix

Initialise $sourceCollection = null up front and drop the redundant $tool instanceof HasSourcesInterface ? ... : null ternary; just pass $sourceCollection to ToolResult directly. Behavior is identical.

+            $sourceCollection = null;
             if ($tool instanceof HasSourcesInterface) {
                 $tool->setSourceCollection($sourceCollection = new SourceCollection());
             }

             $result = new ToolResult(
                 $toolCall,
                 $tool->{$metadata->getReference()->getMethod()}(...$arguments),
-                $tool instanceof HasSourcesInterface ? $sourceCollection : null,
+                $sourceCollection,
             );

Verification

• phpstan analyse src/agent → green
• phpunit on Agent component → 247 tests, 596 assertions, all green

Currently the failure is blocking PHPStan on any Agent-touching PR (and also surfaces on PRs that don't touch Agent, e.g. #2102, because the matrix runs Agent's PHPStan unconditionally).

🤖 Generated with Claude Code

[4lxndr]

#2100 :)