fix(core): resolve nested plan directory duplication and relative path policies (#25138)

packages/core/src/tools/edit.ts

@@ -58,6 +58,7 @@ import { EDIT_DEFINITION } from './definitions/coreTools.js';
 import { resolveToolDeclaration } from './definitions/resolver.js';
 import { detectOmissionPlaceholders } from './omissionPlaceholderDetector.js';
 import { discoverJitContext, appendJitContext } from './jit-context.js';
+import { resolveAndValidatePlanPath } from '../utils/planUtils.js';
 
 const ENABLE_FUZZY_MATCH_RECOVERY = true;
 const FUZZY_MATCH_THRESHOLD = 0.1; // Allow up to 10% weighted difference
@@ -465,11 +466,21 @@ class EditToolInvocation
       () => this.config.getApprovalMode(),
     );
     if (this.config.isPlanMode()) {
-      const safeFilename = path.basename(this.params.file_path);
-      this.resolvedPath = path.join(
-        this.config.storage.getPlansDir(),
-        safeFilename,
-      );
+      try {
+        this.resolvedPath = resolveAndValidatePlanPath(
+          this.params.file_path,
+          this.config.storage.getPlansDir(),
+          this.config.getProjectRoot(),
+        );
+      } catch (e) {
+        debugLogger.error(
+          'Failed to resolve plan path during EditTool invocation setup',
+          e,
+        );
+        // Validation fails, set resolvedPath to something that will fail validation downstream or just the raw path.
+        // It's safer to store it so validation in execute() or getConfirmationDetails() catches it.
+        this.resolvedPath = this.params.file_path;
+      }
     } else if (!path.isAbsolute(this.params.file_path)) {
       const result = correctPath(this.params.file_path, this.config);
       if (result.success) {
@@ -1054,7 +1065,17 @@ export class EditTool
     }
 
     let resolvedPath: string;
-    if (!path.isAbsolute(params.file_path)) {
+    if (this.config.isPlanMode()) {
+      try {
+        resolvedPath = resolveAndValidatePlanPath(
+          params.file_path,
+          this.config.storage.getPlansDir(),
+          this.config.getProjectRoot(),
+        );
+      } catch (err) {
+        return err instanceof Error ? err.message : String(err);
+      }
+    } else if (!path.isAbsolute(params.file_path)) {
       const result = correctPath(params.file_path, this.config);
       if (result.success) {
         resolvedPath = result.correctedPath;