fix(hashline-edit): stabilize TUI diff metadata and output flow

Align edit/write hashline handling with TUI expectations by preserving metadata through tool execution, keeping unified diff raw to avoid duplicated line numbers, and tightening read/write/edit outputs plus tests for reliable agent operation.

src/hooks/hashline-read-enhancer/hook.ts

@@ -52,6 +52,14 @@ function transformOutput(output: string): string {
   return result.join("\n")
 }
 
+function transformWriteOutput(output: string): string {
+  if (!output) {
+    return output
+  }
+  const lines = output.split("\n")
+  return lines.map((line) => (READ_LINE_PATTERN.test(line) ? transformLine(line) : line)).join("\n")
+}
+
 export function createHashlineReadEnhancerHook(
   _ctx: PluginInput,
   config: HashlineReadEnhancerConfig
@@ -70,7 +78,7 @@ export function createHashlineReadEnhancerHook(
       if (!shouldProcess(config)) {
         return
       }
-      output.output = transformOutput(output.output)
+      output.output = input.tool.toLowerCase() === "write" ? transformWriteOutput(output.output) : transformOutput(output.output)
     },
   }
 }

src/hooks/hashline-read-enhancer/index.test.ts

@@ -113,6 +113,26 @@ describe("createHashlineReadEnhancerHook", () => {
       expect(lines[1]).toMatch(/^2:[a-f0-9]{2}\|const y = 2$/)
     })
 
+    it("should transform numbered write lines even when header lines come first", async () => {
+      //#given
+      const hook = createHashlineReadEnhancerHook(mockCtx, createMockConfig(true))
+      const input = { tool: "write", sessionID, callID: "call-1" }
+      const output = {
+        title: "Write",
+        output: ["# Wrote /tmp/demo-edit.txt", "1: This is line one", "2: This is line two"].join("\n"),
+        metadata: {},
+      }
+
+      //#when
+      await hook["tool.execute.after"](input, output)
+
+      //#then
+      const lines = output.output.split("\n")
+      expect(lines[0]).toBe("# Wrote /tmp/demo-edit.txt")
+      expect(lines[1]).toMatch(/^1:[a-f0-9]{2}\|This is line one$/)
+      expect(lines[2]).toMatch(/^2:[a-f0-9]{2}\|This is line two$/)
+    })
+
     it("should skip non-read tools", async () => {
       //#given
       const hook = createHashlineReadEnhancerHook(mockCtx, createMockConfig(true))