diff --git a/docs/coding-agent-notes.md b/docs/coding-agent-notes.md
new file mode 100644
index 00000000..1b31fc36
--- /dev/null
+++ b/docs/coding-agent-notes.md
@@ -0,0 +1,46 @@
+# Coding-Agent Notes
+
+The Gently runtime agent can leave durable notes for a future coding-agent pass with the
+`leave_coding_agent_note` tool. Notes are append-only JSONL records intended for
+bug reports, internal errors, implementation feedback, or user requests that
+should be addressed in code.
+
+When a FileStore session is active, notes are written to:
+
+```text
+<session_dir>/coding_agent_notes.jsonl
+```
+
+If no session directory can be resolved, the fallback path is:
+
+```text
+<agent.storage_path>/coding_agent_notes.jsonl
+```
+
+Each record includes:
+
+- `note_id`
+- `timestamp`
+- `session_id`
+- `category`
+- `severity`
+- `message`
+- optional structured `context`
+
+The companion `list_coding_agent_notes` tool lists recent notes so the operator
+or Gently agent can confirm what has been captured.
+
+Example record:
+
+```json
+{
+  "note_id": "8b4f0bc9e0a1",
+  "timestamp": "2026-05-30T12:00:00",
+  "message": "User expected movement to verify embryo position first.",
+  "session_id": "abc12345",
+  "category": "bug",
+  "severity": "warning",
+  "source": "gently_agent",
+  "context": {"summary": "move_to_embryo skipped position lookup"}
+}
+```
diff --git a/gently/app/tools/__init__.py b/gently/app/tools/__init__.py
index 99c91e34..e1059968 100644
--- a/gently/app/tools/__init__.py
+++ b/gently/app/tools/__init__.py
@@ -22,6 +22,7 @@
 from . import detection_tools
 from . import plan_execution_tools
 from . import memory_tools
+from . import coding_notes_tools
 from . import resolution_tools
 from gently.harness.plan_mode.tools import lab_context as _lab_context  # query_lab_history in run mode
 
diff --git a/gently/app/tools/coding_notes_tools.py b/gently/app/tools/coding_notes_tools.py
new file mode 100644
index 00000000..43ab2e60
--- /dev/null
+++ b/gently/app/tools/coding_notes_tools.py
@@ -0,0 +1,97 @@
+"""Tools for leaving notes to future coding-agent work."""
+
+from typing import Dict, Optional
+
+from gently.harness.coding_notes import CodingNotesStore
+from gently.harness.tools.registry import tool, ToolCategory, ToolExample
+
+
+def _get_notes_store(context: Dict):
+    agent = context.get("agent") if context else None
+    if not agent:
+        return None, None, "Error: No agent context"
+    return CodingNotesStore.for_agent(agent), agent, None
+
+
+@tool(
+    name="leave_coding_agent_note",
+    description=(
+        "Write a persistent note for a future coding agent. Use this when the "
+        "user reports a bug, asks for code changes, gives implementation "
+        "feedback, or when an internal error reveals something maintainers "
+        "should fix later."
+    ),
+    category=ToolCategory.UTILITY,
+    examples=[
+        ToolExample(
+            "Leave a bug note",
+            {
+                "message": "User expected move_to_embryo to verify a stored position first.",
+                "category": "bug",
+                "severity": "warning",
+            },
+        ),
+    ],
+)
+async def leave_coding_agent_note(
+    message: str,
+    category: str = "feedback",
+    severity: str = "info",
+    context_summary: Optional[str] = None,
+    context: Dict = None,
+) -> str:
+    """Persist a coding-agent note."""
+    store, agent, err = _get_notes_store(context)
+    if err:
+        return err
+
+    note_context = {}
+    if context_summary:
+        note_context["summary"] = context_summary
+
+    try:
+        note = store.append_note(
+            message,
+            session_id=getattr(agent, "session_id", None),
+            category=category,
+            severity=severity,
+            context=note_context,
+        )
+    except ValueError as exc:
+        return f"Error writing coding-agent note: {exc}"
+
+    return f"Saved coding-agent note {note.note_id} to {store.path}"
+
+
+@tool(
+    name="list_coding_agent_notes",
+    description=(
+        "List recent persistent notes that were left for a future coding agent. "
+        "Use this to review outstanding bug reports or implementation feedback."
+    ),
+    category=ToolCategory.UTILITY,
+    examples=[
+        ToolExample("Show coding notes", {"limit": 5}),
+    ],
+)
+async def list_coding_agent_notes(
+    limit: int = 10,
+    category: Optional[str] = None,
+    context: Dict = None,
+) -> str:
+    """List recent coding-agent notes."""
+    store, _agent, err = _get_notes_store(context)
+    if err:
+        return err
+
+    notes = store.list_notes(limit=limit, category=category)
+    if not notes:
+        return f"No coding-agent notes found at {store.path}"
+
+    lines = [f"Coding-agent notes ({store.path}):"]
+    for note in notes:
+        lines.append(
+            f"- [{note.severity}/{note.category}] {note.timestamp} "
+            f"{note.note_id}: {note.message}"
+        )
+    return "\n".join(lines)
diff --git a/gently/harness/coding_notes.py b/gently/harness/coding_notes.py
new file mode 100644
index 00000000..64ae969a
--- /dev/null
+++ b/gently/harness/coding_notes.py
@@ -0,0 +1,121 @@
+"""Persistent notes from the Gently agent to a coding agent."""
+
+from __future__ import annotations
+
+import json
+import uuid
+from dataclasses import asdict, dataclass, field
+from datetime import datetime
+from pathlib import Path
+from typing import Any, Dict, List, Mapping, Optional
+
+
+@dataclass(frozen=True)
+class CodingAgentNote:
+    """A structured note intended for a future coding-agent pass."""
+
+    note_id: str
+    timestamp: str
+    message: str
+    session_id: Optional[str] = None
+    category: str = "feedback"
+    severity: str = "info"
+    source: str = "gently_agent"
+    context: Mapping[str, Any] = field(default_factory=dict)
+
+    def to_dict(self) -> Dict[str, Any]:
+        return asdict(self)
+
+    @classmethod
+    def from_dict(cls, data: Mapping[str, Any]) -> "CodingAgentNote":
+        return cls(
+            note_id=str(data.get("note_id", "")),
+            timestamp=str(data.get("timestamp", "")),
+            message=str(data.get("message", "")),
+            session_id=data.get("session_id"),
+            category=str(data.get("category", "feedback")),
+            severity=str(data.get("severity", "info")),
+            source=str(data.get("source", "gently_agent")),
+            context=data.get("context") or {},
+        )
+
+
+class CodingNotesStore:
+    """Append-only JSONL store for coding-agent notes."""
+
+    def __init__(self, path: Path):
+        self.path = Path(path)
+
+    @classmethod
+    def for_agent(cls, agent) -> "CodingNotesStore":
+        """Resolve the best notes path for an agent-like object."""
+        session_id = getattr(agent, "session_id", None)
+        store = getattr(agent, "store", None)
+        if store is not None and session_id and hasattr(store, "_session_dir"):
+            session_dir = store._session_dir(session_id)
+            if session_dir is not None:
+                return cls(session_dir / "coding_agent_notes.jsonl")
+
+        storage_path = Path(getattr(agent, "storage_path", "."))
+        return cls(storage_path / "coding_agent_notes.jsonl")
+
+    def append_note(
+        self,
+        message: str,
+        *,
+        session_id: Optional[str] = None,
+        category: str = "feedback",
+        severity: str = "info",
+        source: str = "gently_agent",
+        context: Optional[Mapping[str, Any]] = None,
+    ) -> CodingAgentNote:
+        """Append a note and return the stored record."""
+        cleaned = message.strip()
+        if not cleaned:
+            raise ValueError("note message cannot be empty")
+
+        note = CodingAgentNote(
+            note_id=uuid.uuid4().hex[:12],
+            timestamp=datetime.now().isoformat(),
+            message=cleaned,
+            session_id=session_id,
+            category=category.strip().lower() or "feedback",
+            severity=severity.strip().lower() or "info",
+            source=source,
+            context=dict(context or {}),
+        )
+
+        self.path.parent.mkdir(parents=True, exist_ok=True)
+        with self.path.open("a", encoding="utf-8") as f:
+            f.write(json.dumps(note.to_dict(), default=str) + "\n")
+        return note
+
+    def list_notes(
+        self,
+        *,
+        limit: Optional[int] = None,
+        category: Optional[str] = None,
+    ) -> List[CodingAgentNote]:
+        """Read notes from newest to oldest."""
+        if not self.path.exists():
+            return []
+
+        wanted_category = category.strip().lower() if category else None
+        notes: List[CodingAgentNote] = []
+        with self.path.open("r", encoding="utf-8") as f:
+            for raw in f:
+                raw = raw.strip()
+                if not raw:
+                    continue
+                try:
+                    note = CodingAgentNote.from_dict(json.loads(raw))
+                except json.JSONDecodeError:
+                    continue
+                if wanted_category and note.category != wanted_category:
+                    continue
+                notes.append(note)
+
+        notes.reverse()
+        if limit is not None:
+            return notes[:max(0, limit)]
+        return notes
diff --git a/tests/test_coding_notes.py b/tests/test_coding_notes.py
new file mode 100644
index 00000000..28d92196
--- /dev/null
+++ b/tests/test_coding_notes.py
@@ -0,0 +1,80 @@
+import json
+from types import SimpleNamespace
+
+import pytest
+
+from gently.app.tools.coding_notes_tools import (
+    leave_coding_agent_note,
+    list_coding_agent_notes,
+)
+from gently.core.file_store import FileStore
+from gently.harness.coding_notes import CodingNotesStore
+
+
+def test_coding_notes_store_appends_and_lists_newest_first(tmp_path):
+    store = CodingNotesStore(tmp_path / "notes.jsonl")
+
+    first = store.append_note("First note", session_id="s1", category="bug")
+    second = store.append_note("Second note", session_id="s1", category="feedback")
+
+    notes = store.list_notes()
+    raw = [
+        json.loads(line)
+        for line in (tmp_path / "notes.jsonl").read_text(encoding="utf-8").splitlines()
+    ]
+
+    assert [note.note_id for note in notes] == [second.note_id, first.note_id]
+    assert raw[0]["message"] == "First note"
+    assert store.list_notes(category="bug")[0].message == "First note"
+
+
+def test_coding_notes_store_rejects_empty_messages(tmp_path):
+    store = CodingNotesStore(tmp_path / "notes.jsonl")
+
+    with pytest.raises(ValueError, match="cannot be empty"):
+        store.append_note("   ")
+
+
+@pytest.mark.asyncio
+async def test_leave_coding_agent_note_tool_writes_to_session_dir(tmp_path):
+    file_store = FileStore(tmp_path)
+    file_store.create_session("abc12345", name="notes")
+    agent = SimpleNamespace(
+        store=file_store,
+        session_id="abc12345",
+        storage_path=tmp_path,
+    )
+
+    result = await leave_coding_agent_note(
+        message="The Gently agent should surface detector errors to the user.",
+        category="bug",
+        severity="warning",
+        context_summary="Detector returned an exception during detection.",
+        context={"agent": agent},
+    )
+
+    session_dir = file_store._session_dir("abc12345")
+    notes_path = session_dir / "coding_agent_notes.jsonl"
+    payload = json.loads(notes_path.read_text(encoding="utf-8").strip())
+
+    assert "Saved coding-agent note" in result
+    assert payload["session_id"] == "abc12345"
+    assert payload["category"] == "bug"
+    assert payload["source"] == "gently_agent"
+    assert payload["context"]["summary"].startswith("Detector returned")
+
+
+@pytest.mark.asyncio
+async def test_list_coding_agent_notes_tool_formats_recent_notes(tmp_path):
+    agent = SimpleNamespace(
+        store=None,
+        session_id=None,
+        storage_path=tmp_path,
+    )
+    store = CodingNotesStore.for_agent(agent)
+    store.append_note("Remember to add a regression test.", category="test")
+
+    result = await list_coding_agent_notes(limit=5, context={"agent": agent})
+
+    assert "Remember to add a regression test." in result
+    assert str(tmp_path / "coding_agent_notes.jsonl") in result