fix(diff): drop the phantom trailing row from every edit's diff

package.json

@@ -1,6 +1,6 @@
 {
   "name": "dsh-cctui",
-  "version": "0.3.9",
+  "version": "0.3.10",
   "description": "Claude-Code-style terminal UI for deepseek-harness, ported from clawcodex ui-tui",
   "license": "MIT",
   "repository": {

scripts/tool-gallery.py

@@ -58,10 +58,13 @@
     "glob": 'PROBE glob {"pattern": "src/components/*.tsx"}',
     "bash": 'PROBE bash {"command": "ls -1 src | head -12", "description": "list src"}',
     "bash_fail": 'PROBE bash {"command": "ls /no/such/dir", "description": "failing ls"}',
-    "write": 'PROBE write {"file_path": "e2e-scratch/gallery.txt", "content": "alpha\\nbeta\\ngamma\\n"}',
+    "write": 'PROBE write {"file_path": "e2e-scratch/gallery-write.txt", "content": "alpha\\nbeta\\ngamma\\n"}',
+    # the harness refuses to edit a file this session has not observed, so the
+    # scenario writes it, reads it, then edits it
     "edit": [
-        'PROBE write {"file_path": "e2e-scratch/gallery.txt", "content": "alpha\\nbeta\\ngamma\\n"}',
-        'PROBE edit {"file_path": "e2e-scratch/gallery.txt", "old_string": "beta", "new_string": "BETA-changed"}',
+        'PROBE write {"file_path": "e2e-scratch/gallery-edit.txt", "content": "alpha\\nbeta\\ngamma\\n"}',
+        'PROBE read {"file_path": "e2e-scratch/gallery-edit.txt"}',
+        'PROBE edit {"file_path": "e2e-scratch/gallery-edit.txt", "old_string": "beta", "new_string": "BETA-changed"}',
     ],
     # reaches the network on purpose — the fetch card is a retrieval summary
     "web_fetch": 'PROBE web_fetch {"url": "https://example.com"}',
@@ -83,7 +86,8 @@
     ),
     "skill": 'PROBE skill {"name": "nonexistent-skill"}',
     "read_image": 'PROBE read_image {"file_path": "e2e-scratch/gallery.png"}',
-    "str_replace_editor": 'PROBE str_replace_editor {"command": "view", "path": "src/domain/usage.ts"}',
+    # this one insists on an absolute path
+    "str_replace_editor": ('PROBE str_replace_editor {"command": "view", "path": "%s/src/domain/usage.ts"}' % ROOT),
     "job_output": 'PROBE job_output {"job_id": "no-such-job"}',
     "send_message": 'PROBE send_message {"subagent_id": "no-such-agent", "message": "hello"}',
     "get_goal": 'PROBE get_goal {}',
@@ -111,6 +115,9 @@
 
 
 def bootstrap() -> None:
+    # the mutation scenarios must CREATE their file, not find yesterday's
+    for leftover in (ROOT / "e2e-scratch").glob("gallery-*.txt"):
+        leftover.unlink()
     PROFILE.mkdir(parents=True, exist_ok=True)
     (PROFILE / "package.json").write_text(
         json.dumps(

src/__tests__/harnessClient.test.ts

@@ -51,7 +51,10 @@ const TOOL_CARDS: Record<string, unknown> = {
     path: 'src/y.ts',
     totalLines: 40
   },
-  write: { card: 'diff', diffs: [{ newText: 'line one\nline two\n', oldText: null, path: 'notes.txt' }] }
+  write: { card: 'diff', diffs: [{ newText: 'line one\nline two\n', oldText: null, path: 'notes.txt' }] },
+  // an APPLIED HUNK rather than a whole file: it stops mid-file, so neither
+  // side carries a trailing newline
+  write_hunk: { card: 'diff', diffs: [{ newText: 'beta\nBETA', oldText: 'beta\nbeta', path: 'notes.txt' }] }
 }
 
 function makeWorld() {
@@ -1024,6 +1027,16 @@ describe('HarnessGatewayClient', () => {
     expect(usage.context_percent).toBe(5)
   })
 
+  it('drops the no-newline marker a hunk-shaped diff always produces', async () => {
+    const done = await runTool('write_hunk', '{"file_path":"notes.txt"}')
+    const lines = done.payload.structured_diff?.hunks.flatMap(hunk => hunk.lines) ?? []
+
+    // the row renderer has no marker for `\ No newline at end of file`, so it
+    // came out as a phantom context line numbered one past the end
+    expect(lines.length).toBeGreaterThan(0)
+    expect(lines.some(line => line.startsWith('\\'))).toBe(false)
+  })
+
   it('converts diff presentation views into structured_diff payloads', async () => {
     const w = makeWorld()
 

src/harness/client.ts

@@ -1092,7 +1092,13 @@ export class HarnessGatewayClient extends GatewayClient {
         const structuredDiff: StructuredDiffPayload = {
           filePath: first.path,
           hunks: patch.hunks.map(h => ({
-            lines: h.lines,
+            // `\ No newline at end of file` is an artifact of diffing the
+            // tool's applied HUNK rather than the whole file: a fragment that
+            // stops mid-file has no trailing newline by construction, and the
+            // file it came from is usually fine. The row renderer has no marker
+            // for it either, so it came out as a phantom context line numbered
+            // one past the end. Upstream shows no such row.
+            lines: h.lines.filter(line => !line.startsWith('\\')),
             newLines: h.newLines,
             newStart: h.newStart,
             oldLines: h.oldLines,