feat(core): pass resolved plan directory context to tools and system prompt via activeExtensionName

packages/core/src/config/agent-loop-context.ts

@@ -26,6 +26,9 @@ export interface AgentLoopContext {
   /** The unique ID for the parent session if this is a subagent. */
   readonly parentSessionId?: string;
 
+  /** The name of the active extension driving this context, if any. */
+  readonly activeExtensionName?: string;
+
   /** The registry of tools available to the agent in this context. */
   readonly toolRegistry: ToolRegistry;
 

packages/core/src/config/config.ts

@@ -737,6 +737,17 @@ export class Config implements McpContext, AgentLoopContext {
   private blockedEnvironmentVariables: string[];
   private readonly enableEnvironmentVariableRedaction: boolean;
   private _promptRegistry!: PromptRegistry;
+  private _activeExtensionName?: string;
+
+  get activeExtensionName(): string | undefined {
+    return (
+      this._activeExtensionName || process.env['GEMINI_CLI_ACTIVE_EXTENSION']
+    );
+  }
+
+  setActiveExtensionName(name: string | undefined): void {
+    this._activeExtensionName = name;
+  }
   private _resourceRegistry!: ResourceRegistry;
   private agentRegistry!: AgentRegistry;
   private readonly acknowledgedAgentsService: AcknowledgedAgentsService;

packages/core/src/prompts/promptProvider.ts

@@ -192,12 +192,28 @@ export class PromptProvider {
         ),
         planningWorkflow: this.withSection(
           'planningWorkflow',
-          () => ({
-            interactive: interactiveMode,
-            planModeToolsList,
-            plansDir: context.config.storage.getPlansDir(),
-            approvedPlanPath: context.config.getApprovedPlanPath(),
-          }),
+          () => {
+            let plansDir = '';
+            const activeExt = context.config.activeExtensionName;
+            let customDir: string | undefined;
+            if (activeExt) {
+              customDir = context.config.getExtensionSetting<string>(
+                activeExt,
+                'plan.directory',
+              );
+            }
+            try {
+              plansDir = context.config.storage.getPlansDir(customDir);
+            } catch {
+              // ignore
+            }
+            return {
+              interactive: interactiveMode,
+              planModeToolsList,
+              plansDir,
+              approvedPlanPath: context.config.getApprovedPlanPath(),
+            };
+          },
           isPlanMode,
         ),
         operationalGuidelines: this.withSection(

packages/core/src/tools/edit.ts

@@ -466,10 +466,22 @@ class EditToolInvocation
     );
     if (this.config.isPlanMode()) {
       const safeFilename = path.basename(this.params.file_path);
-      this.resolvedPath = path.join(
-        this.config.storage.getPlansDir(),
-        safeFilename,
-      );
+      let customDir: string | undefined;
+      const activeExt = this.config.activeExtensionName;
+      if (activeExt) {
+        customDir = this.config.getExtensionSetting<string>(
+          activeExt,
+          'plan.directory',
+        );
+      }
+      try {
+        this.resolvedPath = path.join(
+          this.config.storage.getPlansDir(customDir),
+          safeFilename,
+        );
+      } catch {
+        this.resolvedPath = ''; // Handled safely downstream
+      }
     } else if (!path.isAbsolute(this.params.file_path)) {
       const result = correctPath(this.params.file_path, this.config);
       if (result.success) {

packages/core/src/tools/exit-plan-mode.ts

@@ -53,6 +53,18 @@ export class ExitPlanModeTool extends BaseDeclarativeTool<
     );
   }
 
+  private getResolvedPlansDir(): string {
+    let customDir: string | undefined;
+    const activeExt = this.config.activeExtensionName;
+    if (activeExt) {
+      customDir = this.config.getExtensionSetting<string>(
+        activeExt,
+        'plan.directory',
+      );
+    }
+    return this.config.storage.getPlansDir(customDir);
+  }
+
   protected override validateToolParamValues(
     params: ExitPlanModeParams,
   ): string | null {
@@ -61,11 +73,14 @@ export class ExitPlanModeTool extends BaseDeclarativeTool<
     }
 
     const safeFilename = path.basename(params.plan_filename);
-    const plansDir = resolveToRealPath(this.config.storage.getPlansDir());
-    const resolvedPath = path.join(
-      this.config.storage.getPlansDir(),
-      safeFilename,
-    );
+    let plansDir: string;
+    let resolvedPath: string;
+    try {
+      plansDir = resolveToRealPath(this.getResolvedPlansDir());
+      resolvedPath = path.join(this.getResolvedPlansDir(), safeFilename);
+    } catch {
+      return 'Failed to read plan directory: Path traversal attempt detected.';
+    }
 
     const realPath = resolveToRealPath(resolvedPath);
 
@@ -114,6 +129,18 @@ export class ExitPlanModeInvocation extends BaseToolInvocation<
     super(params, messageBus, toolName, toolDisplayName);
   }
 
+  private getResolvedPlansDir(): string {
+    let customDir: string | undefined;
+    const activeExt = this.config.activeExtensionName;
+    if (activeExt) {
+      customDir = this.config.getExtensionSetting<string>(
+        activeExt,
+        'plan.directory',
+      );
+    }
+    return this.config.storage.getPlansDir(customDir);
+  }
+
   override async shouldConfirmExecute(
     abortSignal: AbortSignal,
   ): Promise<ToolExitPlanModeConfirmationDetails | false> {
@@ -121,7 +148,7 @@ export class ExitPlanModeInvocation extends BaseToolInvocation<
 
     const pathError = await validatePlanPath(
       this.params.plan_filename,
-      this.config.storage.getPlansDir(),
+      this.getResolvedPlansDir(),
     );
     if (pathError) {
       this.planValidationError = pathError;
@@ -171,7 +198,7 @@ export class ExitPlanModeInvocation extends BaseToolInvocation<
   }
 
   getDescription(): string {
-    return `Requesting plan approval for: ${path.join(this.config.storage.getPlansDir(), this.params.plan_filename)}`;
+    return `Requesting plan approval for: ${path.join(this.getResolvedPlansDir(), this.params.plan_filename)}`;
   }
 
   /**
@@ -180,7 +207,7 @@ export class ExitPlanModeInvocation extends BaseToolInvocation<
    */
   private getResolvedPlanPath(): string {
     const safeFilename = path.basename(this.params.plan_filename);
-    return path.join(this.config.storage.getPlansDir(), safeFilename);
+    return path.join(this.getResolvedPlansDir(), safeFilename);
   }
 
   async execute({ abortSignal: _signal }: ExecuteOptions): Promise<ToolResult> {

packages/core/src/tools/tool-registry.ts

@@ -634,7 +634,23 @@ export class ToolRegistry {
    */
   getFunctionDeclarations(modelId?: string): FunctionDeclaration[] {
     const isPlanMode = this.config.getApprovalMode() === ApprovalMode.PLAN;
-    const plansDir = this.config.storage.getPlansDir();
+
+    let plansDir: string | undefined;
+    if (isPlanMode) {
+      let customDir: string | undefined;
+      const activeExt = this.config.activeExtensionName;
+      if (activeExt) {
+        customDir = this.config.getExtensionSetting<string>(
+          activeExt,
+          'plan.directory',
+        );
+      }
+      try {
+        plansDir = this.config.storage.getPlansDir(customDir);
+      } catch {
+        // ignore
+      }
+    }
 
     const declarations: FunctionDeclaration[] = [];
     const seenNames = new Set<string>();

packages/core/src/tools/tools.ts

@@ -38,6 +38,7 @@ export interface ExecuteOptions {
   updateOutput?: (output: ToolLiveOutput) => void;
   shellExecutionConfig?: ShellExecutionConfig;
   setExecutionIdCallback?: (executionId: number) => void;
+  activeExtensionName?: string;
 }
 
 /**

packages/core/src/tools/write-file.ts

@@ -169,10 +169,22 @@ class WriteFileToolInvocation extends BaseToolInvocation<
 
     if (this.config.isPlanMode()) {
       const safeFilename = path.basename(this.params.file_path);
-      this.resolvedPath = path.join(
-        this.config.storage.getPlansDir(),
-        safeFilename,
-      );
+      let customDir: string | undefined;
+      const activeExt = this.config.activeExtensionName;
+      if (activeExt) {
+        customDir = this.config.getExtensionSetting<string>(
+          activeExt,
+          'plan.directory',
+        );
+      }
+      try {
+        this.resolvedPath = path.join(
+          this.config.storage.getPlansDir(customDir),
+          safeFilename,
+        );
+      } catch {
+        this.resolvedPath = ''; // handled safely downstream
+      }
     } else {
       this.resolvedPath = path.resolve(
         this.config.getTargetDir(),