feat(tools): tighten patch and session workflows

nanobot/agent/tools/apply_patch.py

@@ -10,7 +10,7 @@ from typing import Any, Literal
 
 from nanobot.agent.tools.base import tool_parameters
 from nanobot.agent.tools.filesystem import _FsTool
-from nanobot.agent.tools.schema import StringSchema, tool_parameters_schema
+from nanobot.agent.tools.schema import BooleanSchema, StringSchema, tool_parameters_schema
 
 
 PatchKind = Literal["add", "delete", "update"]
@@ -31,6 +31,15 @@ class _PatchOp:
     hunks: list[_Hunk] | None = None
 
 
+@dataclass(slots=True)
+class _PatchSummary:
+    action: str
+    path: str
+    added: int = 0
+    deleted: int = 0
+    new_path: str | None = None
+
+
 class _PatchError(ValueError):
     pass
 
@@ -65,6 +74,40 @@ def _lines_to_text(lines: list[str]) -> str:
     return "\n".join(lines) + "\n"
 
 
+def _text_line_count(text: str) -> int:
+    if not text:
+        return 0
+    return len(text.splitlines())
+
+
+def _line_diff_stats(before: str, after: str) -> tuple[int, int]:
+    before_lines = before.replace("\r\n", "\n").splitlines()
+    after_lines = after.replace("\r\n", "\n").splitlines()
+    added = 0
+    deleted = 0
+    matcher = difflib.SequenceMatcher(a=before_lines, b=after_lines, autojunk=False)
+    for tag, i1, i2, j1, j2 in matcher.get_opcodes():
+        if tag == "equal":
+            continue
+        if tag in ("replace", "delete"):
+            deleted += i2 - i1
+        if tag in ("replace", "insert"):
+            added += j2 - j1
+    return added, deleted
+
+
+def _format_summary(summary: _PatchSummary) -> str:
+    path = (
+        f"{summary.path} -> {summary.new_path}"
+        if summary.new_path
+        else summary.path
+    )
+    stats = ""
+    if summary.added or summary.deleted:
+        stats = f" (+{summary.added}/-{summary.deleted})"
+    return f"- {summary.action} {path}{stats}"
+
+
 def _parse_patch(patch: str) -> list[_PatchOp]:
     lines = patch.replace("\r\n", "\n").replace("\r", "\n").split("\n")
     if lines and lines[-1] == "":
@@ -237,6 +280,10 @@ def _apply_hunks(path: str, content: str, hunks: list[_Hunk]) -> str:
             "for Add File, Update File, Delete File, and optional Move to.",
             min_length=1,
         ),
+        dry_run=BooleanSchema(
+            description="Validate and summarize the patch without writing files.",
+            default=False,
+        ),
         required=["patch"],
     )
 )
@@ -255,39 +302,63 @@ class ApplyPatchTool(_FsTool):
             "*** Begin Patch and *** End Patch. Supports Add File, Update File, "
             "Delete File, and Move to. Paths must be relative. Prefer this for "
             "multi-file coding changes; use edit_file for small exact replacements. "
+            "Set dry_run=true to validate and preview the change without writing files."
         )
 
-    async def execute(self, patch: str, **kwargs: Any) -> str:
+    async def execute(self, patch: str, dry_run: bool = False, **kwargs: Any) -> str:
         try:
             ops = _parse_patch(patch)
             writes: dict[Path, str] = {}
             deletes: set[Path] = set()
-            touched: list[str] = []
+            summaries: list[_PatchSummary] = []
 
             for op in ops:
                 source = self._resolve(op.path)
                 if op.kind == "add":
-                    if source.exists():
+                    if source.exists() or source in writes:
                         raise _PatchError(f"file to add already exists: {op.path}")
-                    writes[source] = _lines_to_text(op.add_lines or [])
+                    new_content = _lines_to_text(op.add_lines or [])
+                    writes[source] = new_content
                     deletes.discard(source)
-                    touched.append(f"add {op.path}")
+                    summaries.append(_PatchSummary(
+                        action="add",
+                        path=op.path,
+                        added=_text_line_count(new_content),
+                    ))
                     continue
 
                 if op.kind == "delete":
-                    if not source.exists():
+                    pending_content = writes.get(source)
+                    if pending_content is None and not source.exists():
                         raise _PatchError(f"file to delete does not exist: {op.path}")
-                    if not source.is_file():
+                    if pending_content is None and not source.is_file():
                         raise _PatchError(f"path to delete is not a file: {op.path}")
+                    deleted_lines = 0
+                    if pending_content is not None:
+                        deleted_lines = _text_line_count(pending_content)
+                    else:
+                        raw = source.read_bytes()
+                        try:
+                            deleted_lines = _text_line_count(raw.decode("utf-8"))
+                        except UnicodeDecodeError:
+                            deleted_lines = 0
                     deletes.add(source)
                     writes.pop(source, None)
-                    touched.append(f"delete {op.path}")
+                    summaries.append(_PatchSummary(
+                        action="delete",
+                        path=op.path,
+                        deleted=deleted_lines,
+                    ))
                     continue
 
-                if not source.exists():
+                pending_content = writes.get(source)
+                if pending_content is None and not source.exists():
                     raise _PatchError(f"file to update does not exist: {op.path}")
-                if not source.is_file():
+                if pending_content is None and not source.is_file():
                     raise _PatchError(f"path to update is not a file: {op.path}")
+                if pending_content is not None:
+                    content = pending_content
+                else:
                     raw = source.read_bytes()
                     try:
                         content = raw.decode("utf-8")
@@ -296,18 +367,31 @@ class ApplyPatchTool(_FsTool):
                 uses_crlf = "\r\n" in content
                 content = content.replace("\r\n", "\n")
                 new_content = _apply_hunks(op.path, content, op.hunks or [])
+                added, deleted = _line_diff_stats(content, new_content)
                 if uses_crlf:
                     new_content = new_content.replace("\n", "\r\n")
 
                 target = self._resolve(op.new_path) if op.new_path else source
-                if op.new_path and target.exists() and target != source:
+                if op.new_path and (target.exists() or target in writes) and target != source:
                     raise _PatchError(f"move target already exists: {op.new_path}")
                 writes[target] = new_content
                 deletes.discard(target)
                 if target != source:
                     deletes.add(source)
-                action = f"move {op.path} -> {op.new_path}" if op.new_path else f"update {op.path}"
-                touched.append(action)
+                    writes.pop(source, None)
+                summaries.append(_PatchSummary(
+                    action="move" if op.new_path else "update",
+                    path=op.path,
+                    new_path=op.new_path,
+                    added=added,
+                    deleted=deleted,
+                ))
+
+            if dry_run:
+                return (
+                    "Patch dry-run succeeded:\n"
+                    + "\n".join(_format_summary(summary) for summary in summaries)
+                )
 
             backups: dict[Path, bytes | None] = {}
             for path in set(writes) | deletes:
@@ -332,7 +416,10 @@ class ApplyPatchTool(_FsTool):
 
             for path in set(writes) | deletes:
                 self._file_states.record_write(path)
-            return "Patch applied:\n" + "\n".join(f"- {item}" for item in touched)
+            return (
+                "Patch applied:\n"
+                + "\n".join(_format_summary(summary) for summary in summaries)
+            )
         except PermissionError as exc:
             return f"Error: {exc}"
         except _PatchError as exc:

nanobot/agent/tools/exec_session.py

@@ -16,6 +16,8 @@ from nanobot.agent.tools.schema import BooleanSchema, IntegerSchema, StringSchem
 
 DEFAULT_YIELD_MS = 1000
 MAX_YIELD_MS = 30_000
+DEFAULT_WAIT_FOR_MS = 10_000
+MAX_WAIT_FOR_MS = 120_000
 DEFAULT_MAX_OUTPUT_CHARS = 10_000
 MAX_OUTPUT_CHARS = 50_000
 
@@ -356,6 +358,18 @@ def format_session_poll(session_id: str, poll: _SessionPoll) -> str:
             minimum=0,
             maximum=MAX_YIELD_MS,
         ),
+        wait_for=StringSchema(
+            "Optional text to wait for in output before returning. "
+            "Useful for interactive commands and dev servers.",
+            nullable=True,
+        ),
+        wait_timeout_ms=IntegerSchema(
+            DEFAULT_WAIT_FOR_MS,
+            description="Maximum milliseconds to wait for wait_for text (default 10000, max 120000).",
+            minimum=0,
+            maximum=MAX_WAIT_FOR_MS,
+            nullable=True,
+        ),
         max_output_chars=IntegerSchema(
             DEFAULT_MAX_OUTPUT_CHARS,
             description="Maximum output characters to return from this poll (default 10000, max 50000).",
@@ -412,8 +426,9 @@ class WriteStdinTool(Tool):
         return (
             "Write text to a running exec session and return recent output. "
             "Use chars='' to poll without writing. Set close_stdin=true to send EOF, "
-            "or terminate=true to stop the session. Sessions finish automatically "
-            "when their process exits."
+            "or terminate=true to stop the session. Use wait_for to keep polling "
+            "until expected output appears. Sessions finish automatically when "
+            "their process exits."
         )
 
     async def execute(
@@ -423,6 +438,8 @@ class WriteStdinTool(Tool):
         close_stdin: bool = False,
         terminate: bool = False,
         yield_time_ms: int | None = None,
+        wait_for: str | None = None,
+        wait_timeout_ms: int | None = None,
         max_output_chars: int | None = None,
         max_output_tokens: int | None = None,
         **kwargs: Any,
@@ -430,18 +447,34 @@ class WriteStdinTool(Tool):
         try:
             if max_output_chars is None:
                 max_output_chars = max_output_tokens
+            output_limit = clamp_session_int(
+                max_output_chars,
+                DEFAULT_MAX_OUTPUT_CHARS,
+                1000,
+                MAX_OUTPUT_CHARS,
+            )
+            if wait_for:
+                return await self._wait_for_output(
+                    session_id=session_id,
+                    chars=chars,
+                    close_stdin=close_stdin,
+                    terminate=terminate,
+                    wait_for=wait_for,
+                    wait_timeout_ms=clamp_session_int(
+                        wait_timeout_ms,
+                        DEFAULT_WAIT_FOR_MS,
+                        0,
+                        MAX_WAIT_FOR_MS,
+                    ),
+                    max_output_chars=output_limit,
+                )
             poll = await self._manager.write(
                 session_id=session_id,
                 chars=chars,
                 close_stdin=close_stdin,
                 terminate=terminate,
                 yield_time_ms=clamp_session_int(yield_time_ms, DEFAULT_YIELD_MS, 0, MAX_YIELD_MS),
-                max_output_chars=clamp_session_int(
-                    max_output_chars,
-                    DEFAULT_MAX_OUTPUT_CHARS,
-                    1000,
-                    MAX_OUTPUT_CHARS,
-                ),
+                max_output_chars=output_limit,
             )
             return format_session_poll(session_id, poll)
         except KeyError:
@@ -449,6 +482,47 @@ class WriteStdinTool(Tool):
         except Exception as exc:
             return f"Error writing to exec session: {exc}"
 
+    async def _wait_for_output(
+        self,
+        *,
+        session_id: str,
+        chars: str | None,
+        close_stdin: bool,
+        terminate: bool,
+        wait_for: str,
+        wait_timeout_ms: int,
+        max_output_chars: int,
+    ) -> str:
+        deadline = time.monotonic() + (wait_timeout_ms / 1000)
+        aggregate: list[str] = []
+        first = True
+        poll: _SessionPoll | None = None
+
+        while True:
+            remaining_ms = max(0, int((deadline - time.monotonic()) * 1000))
+            step_ms = min(500, remaining_ms)
+            poll = await self._manager.write(
+                session_id=session_id,
+                chars=chars if first else None,
+                close_stdin=close_stdin if first else False,
+                terminate=terminate if first else False,
+                yield_time_ms=step_ms,
+                max_output_chars=max_output_chars,
+            )
+            first = False
+            if poll.output:
+                aggregate.append(poll.output)
+                joined = "".join(aggregate)
+                if wait_for in joined:
+                    poll.output = joined
+                    return format_session_poll(session_id, poll)
+            if poll.done or remaining_ms <= 0:
+                poll.output = "".join(aggregate)
+                result = format_session_poll(session_id, poll)
+                if wait_for not in poll.output:
+                    result += f"\nWait target not observed: {wait_for!r}"
+                return result
+
 
 @tool_parameters(tool_parameters_schema())
 class ListExecSessionsTool(Tool):

nanobot/utils/file_edit_events.py

@@ -219,6 +219,8 @@ def _resolve_apply_patch_paths(
     patch = params.get("patch")
     if not isinstance(patch, str) or not patch.strip():
         return []
+    if params.get("dry_run") is True:
+        return []
     try:
         from nanobot.agent.tools.apply_patch import _parse_patch
 

tests/tools/test_apply_patch_tool.py

@@ -40,9 +40,58 @@ def test_apply_patch_updates_multiple_hunks(tmp_path):
     ))
 
     assert "update multi.txt" in result
+    assert "(+2/-2)" in result
     assert target.read_text() == "line1\nchanged2\nline3\nchanged4\n"
 
 
+def test_apply_patch_dry_run_validates_without_writing(tmp_path):
+    target = tmp_path / "dry.txt"
+    target.write_text("before\n")
+    tool = ApplyPatchTool(workspace=tmp_path)
+
+    result = asyncio.run(tool.execute(
+        patch="""*** Begin Patch
+*** Update File: dry.txt
+@@
+-before
++after
+*** Add File: added.txt
++new
+*** End Patch
+""",
+        dry_run=True,
+    ))
+
+    assert "Patch dry-run succeeded" in result
+    assert "- update dry.txt (+1/-1)" in result
+    assert "- add added.txt (+1/-0)" in result
+    assert target.read_text() == "before\n"
+    assert not (tmp_path / "added.txt").exists()
+
+
+def test_apply_patch_applies_repeated_update_sections_sequentially(tmp_path):
+    target = tmp_path / "repeat.txt"
+    target.write_text("one\ntwo\nthree\n")
+    tool = ApplyPatchTool(workspace=tmp_path)
+
+    result = asyncio.run(tool.execute(
+        patch="""*** Begin Patch
+*** Update File: repeat.txt
+@@
+-one
++ONE
+*** Update File: repeat.txt
+@@
+-three
++THREE
+*** End Patch
+"""
+    ))
+
+    assert result.count("update repeat.txt") == 2
+    assert target.read_text() == "ONE\ntwo\nTHREE\n"
+
+
 def test_apply_patch_ignores_standard_no_newline_marker(tmp_path):
     target = tmp_path / "plain.txt"
     target.write_text("before")

tests/tools/test_exec_session_tools.py

@@ -245,6 +245,65 @@ def test_write_stdin_preserves_completed_session_output_until_polled(tmp_path):
     assert "Exit code: 0" in final
 
 
+def test_write_stdin_can_wait_for_expected_output(tmp_path):
+    async def run() -> tuple[str, str, str]:
+        manager = ExecSessionManager()
+        exec_tool = ExecTool(working_dir=str(tmp_path), timeout=5, session_manager=manager)
+        stdin_tool = WriteStdinTool(manager=manager)
+        command = _python_command(
+            "import time; print('booting', flush=True); "
+            "time.sleep(0.4); print('ready', flush=True); time.sleep(5)"
+        )
+
+        initial = await exec_tool.execute(command=command, yield_time_ms=100)
+        sid = _session_id(initial)
+        waited = await stdin_tool.execute(
+            session_id=sid,
+            wait_for="ready",
+            wait_timeout_ms=3000,
+            yield_time_ms=0,
+        )
+        cleanup = await stdin_tool.execute(session_id=sid, terminate=True, yield_time_ms=0)
+        return initial, waited, cleanup
+
+    initial, waited, cleanup = asyncio.run(run())
+
+    assert "Process running" in initial
+    assert "booting" in waited
+    assert "ready" in waited
+    assert "Wait target not observed" not in waited
+    assert "Session terminated." in cleanup
+
+
+def test_write_stdin_wait_for_reports_timeout_without_killing_session(tmp_path):
+    async def run() -> tuple[str, str, str]:
+        manager = ExecSessionManager()
+        exec_tool = ExecTool(working_dir=str(tmp_path), timeout=5, session_manager=manager)
+        stdin_tool = WriteStdinTool(manager=manager)
+        command = _python_command(
+            "import time; print('booting', flush=True); time.sleep(5)"
+        )
+
+        initial = await exec_tool.execute(command=command, yield_time_ms=100)
+        sid = _session_id(initial)
+        waited = await stdin_tool.execute(
+            session_id=sid,
+            wait_for="never-ready",
+            wait_timeout_ms=200,
+            yield_time_ms=0,
+        )
+        cleanup = await stdin_tool.execute(session_id=sid, terminate=True, yield_time_ms=0)
+        return initial, waited, cleanup
+
+    initial, waited, cleanup = asyncio.run(run())
+
+    assert "Process running" in initial
+    assert "booting" in waited
+    assert "Process running" in waited
+    assert "Wait target not observed: 'never-ready'" in waited
+    assert "Session terminated." in cleanup
+
+
 def test_exec_session_mode_reuses_exec_safety_guard(tmp_path):
     manager = ExecSessionManager()
     tool = ExecTool(

tests/utils/test_file_edit_events.py

@@ -125,6 +125,28 @@ def test_apply_patch_prepares_trackers_for_each_touched_file(tmp_path: Path) ->
     assert (by_path["src/delete_me.py"]["added"], by_path["src/delete_me.py"]["deleted"]) == (0, 1)
 
 
+def test_apply_patch_dry_run_does_not_prepare_file_edit_trackers(tmp_path: Path) -> None:
+    (tmp_path / "file.txt").write_text("old\n", encoding="utf-8")
+
+    trackers = prepare_file_edit_trackers(
+        call_id="call-patch",
+        tool_name="apply_patch",
+        tool=None,
+        workspace=tmp_path,
+        params={
+            "dry_run": True,
+            "patch": """*** Begin Patch
+*** Update File: file.txt
+@@
+-old
++new
+*** End Patch""",
+        },
+    )
+
+    assert trackers == []
+
+
 def test_oversized_write_file_end_uses_known_content_for_exact_count(tmp_path: Path) -> None:
     target = tmp_path / "large.txt"
     params = {"path": "large.txt", "content": "x" * (2 * 1024 * 1024 + 1)}