fix(core): add mutation permission previews (#39578)

packages/core/test/tool-edit.test.ts

@@ -179,6 +179,17 @@ describe("EditTool", () => {
                 })
                 expect(yield* Effect.promise(() => fs.readFile(target, "utf8"))).toBe("after\nrest\n")
                 expect(assertions).toMatchObject([{ sessionID, action: "edit", resources: ["hello.txt"], save: ["*"] }])
+                expect(assertions[0]?.metadata).toMatchObject({
+                  files: [
+                    {
+                      file: "hello.txt",
+                      status: "modified",
+                      additions: 1,
+                      deletions: 1,
+                      patch: expect.stringContaining("-before\n+after"),
+                    },
+                  ],
+                })
                 expect(writes).toEqual([yield* Effect.promise(() => fs.realpath(target))])
               }),
             ),
@@ -343,7 +354,7 @@ describe("EditTool", () => {
             error: { type: "permission.rejected", message: "Permission denied: edit" },
           })
           expect(assertions.map((input) => input.action)).toEqual(["external_directory", "edit"])
-          expect(reads).toBe(0)
+          expect(reads).toBe(1)
           expect(writes).toEqual([])
           expect(yield* Effect.promise(() => fs.readFile(external, "utf8"))).toBe("before")
         }),
@@ -354,7 +365,7 @@ describe("EditTool", () => {
     ),
   )
 
-  it.live("denied edit reads no target content and does not disclose whether oldString matches", () =>
+  it.live("denied edit does not disclose whether oldString matches", () =>
     Effect.acquireUseRelease(
       Effect.promise(() => tmpdir()),
       (tmp) => {
@@ -380,7 +391,7 @@ describe("EditTool", () => {
                 })
                 expect(missing).toEqual(matching)
                 expect(assertions.map((input) => input.action)).toEqual(["edit", "edit"])
-                expect(reads).toBe(0)
+                expect(reads).toBe(2)
                 expect(writes).toEqual([])
               }),
             ),

packages/core/test/tool-write.test.ts

@@ -140,6 +140,17 @@ describe("WriteTool", () => {
               "created",
             )
             expect(assertions).toMatchObject([{ sessionID, action: "edit", resources: ["src/new.txt"], save: ["*"] }])
+            expect(assertions[0]?.metadata).toMatchObject({
+              files: [
+                {
+                  file: "src/new.txt",
+                  status: "added",
+                  additions: 1,
+                  deletions: 0,
+                  patch: expect.stringContaining("+created"),
+                },
+              ],
+            })
             expect(writes).toEqual([path.join(yield* Effect.promise(() => fs.realpath(tmp.path)), "src", "new.txt")])
           }),
         )
@@ -187,6 +198,17 @@ describe("WriteTool", () => {
               if (settled.status !== "completed") return
               expect(settled.content).toEqual([{ type: "text", text: "Wrote file successfully: existing.txt" }])
               expect(settled.output).toMatchObject({ resource: "existing.txt", existed: true })
+              expect(assertions[0]?.metadata).toMatchObject({
+                files: [
+                  {
+                    file: "existing.txt",
+                    status: "modified",
+                    additions: 1,
+                    deletions: 1,
+                    patch: expect.stringMatching(/-before[\s\S]*\+after/),
+                  },
+                ],
+              })
               expect(yield* Effect.promise(() => fs.readFile(path.join(tmp.path, "existing.txt"), "utf8"))).toBe(
                 "after",
               )