fix(agents): skip bootstrap files with undefined path (#22698)

* fix(agents): skip bootstrap files with undefined path

buildBootstrapContextFiles() called file.path.replace() without checking
that path was defined. If a hook pushed a bootstrap file using 'filePath'
instead of 'path', the function threw TypeError and crashed every agent
session — not just the misconfigured hook.

Fix: add a null-guard before the path.replace() call. Files with undefined
path are skipped with a warning so one bad hook can't take down all agents.

Also adds a test covering the undefined-path case.

Fixes #22693

* fix: harden bootstrap path validation and report guards (#22698) (thanks @arosstale)

---------

Co-authored-by: Peter Steinberger <steipete@gmail.com>

src/agents/system-prompt-report.test.ts

@@ -93,4 +93,23 @@ describe("buildSystemPromptReport", () => {
     expect(report.injectedWorkspaceFiles[0]?.injectedChars).toBe(0);
     expect(report.injectedWorkspaceFiles[0]?.truncated).toBe(true);
   });
+
+  it("ignores malformed injected file paths and still matches valid entries", () => {
+    const file = makeBootstrapFile({ path: "/tmp/workspace/policies/AGENTS.md" });
+    const report = buildSystemPromptReport({
+      source: "run",
+      generatedAt: 0,
+      bootstrapMaxChars: 20_000,
+      systemPrompt: "system",
+      bootstrapFiles: [file],
+      injectedFiles: [
+        { path: 123 as unknown as string, content: "bad" },
+        { path: "/tmp/workspace/policies/AGENTS.md", content: "trimmed" },
+      ],
+      skillsPrompt: "",
+      tools: [],
+    });
+
+    expect(report.injectedWorkspaceFiles[0]?.injectedChars).toBe("trimmed".length);
+  });
 });