feat: add reminders_remove tool for single-reminder removal

- reminders_remove(index) removes one reminder by 1-based index
- reminders_list now returns numbered output (1. heading / body)
  so any model can easily identify which index to pass
- _parse_sections() / _sections_to_text() helpers for clean round-trip
- Not in CONFIRM_REQUIRED — targeted removal is safe without a gate

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/tools/reminders.py

@@ -27,6 +27,28 @@ def _now_label() -> str:
     return datetime.now(timezone.utc).strftime("%Y-%m-%d %H:%M UTC")
 
 
+def _parse_sections(text: str) -> list[tuple[str, str]]:
+    """Split REMINDERS.md into (heading, body) tuples, one per ## section."""
+    sections: list[tuple[str, str]] = []
+    heading: str | None = None
+    body_lines: list[str] = []
+    for line in text.splitlines():
+        if line.startswith("## "):
+            if heading is not None:
+                sections.append((heading, "\n".join(body_lines).strip()))
+            heading = line[3:].strip()
+            body_lines = []
+        elif heading is not None:
+            body_lines.append(line)
+    if heading is not None:
+        sections.append((heading, "\n".join(body_lines).strip()))
+    return sections
+
+
+def _sections_to_text(sections: list[tuple[str, str]]) -> str:
+    return "".join(f"\n## {h}\n\n{b}\n" for h, b in sections)
+
+
 # ---------------------------------------------------------------------------
 # Sync implementations
 # ---------------------------------------------------------------------------
@@ -35,7 +57,18 @@ def _reminders_list() -> str:
     p = _reminders_path()
     if not p.exists() or not p.read_text().strip():
         return "No pending reminders."
-    return p.read_text()
+    sections = _parse_sections(p.read_text())
+    if not sections:
+        return "No pending reminders."
+    lines = []
+    for i, (heading, body) in enumerate(sections, 1):
+        lines.append(f"{i}. {heading}")
+        if body:
+            # Indent body so it reads as belonging to the numbered item
+            for bline in body.splitlines()[:4]:  # cap at 4 lines for brevity
+                lines.append(f"   {bline}")
+        lines.append("")
+    return "\n".join(lines).rstrip()
 
 
 def _reminders_add(text: str, label: str | None = None) -> str:
@@ -47,6 +80,26 @@ def _reminders_add(text: str, label: str | None = None) -> str:
     return f"Reminder added: {heading}"
 
 
+def _reminders_remove(index: int) -> str:
+    p = _reminders_path()
+    if not p.exists() or not p.read_text().strip():
+        return "No reminders to remove."
+    sections = _parse_sections(p.read_text())
+    if not sections:
+        return "No reminders to remove."
+    if index < 1 or index > len(sections):
+        return (
+            f"Index {index} is out of range. "
+            f"There {'is' if len(sections) == 1 else 'are'} {len(sections)} "
+            f"reminder{'s' if len(sections) != 1 else ''} (1–{len(sections)}). "
+            "Call reminders_list to see them."
+        )
+    removed_heading = sections[index - 1][0]
+    sections.pop(index - 1)
+    p.write_text(_sections_to_text(sections))
+    return f"Removed reminder {index}: {removed_heading}"
+
+
 def _reminders_clear() -> str:
     p = _reminders_path()
     p.write_text("")
@@ -65,5 +118,9 @@ async def reminders_add(text: str, label: str | None = None) -> str:
     return await asyncio.to_thread(_reminders_add, text, label)
 
 
+async def reminders_remove(index: int) -> str:
+    return await asyncio.to_thread(_reminders_remove, index)
+
+
 async def reminders_clear() -> str:
     return await asyncio.to_thread(_reminders_clear)