fix: python 3.6 compat + clarify CURRENT_STATE.md override rule

SKILL.md

@@ -130,6 +130,22 @@ Update the file by **overwriting** it, not appending, at these moments:
 | Before handoff / subagent exit | Preserves outputs and unsurfaced results |
 | After a substantive state change | Keeps checkpoint aligned with actual work |
 
+### Override rule
+
+**CURRENT_STATE.md must always be overwritten when:**
+- A new task or objective starts — regardless of what is currently in the file
+- The previous objective is complete or abandoned
+- The user gives a new task that supersedes the previous one
+
+Having content in CURRENT_STATE.md does NOT mean it should be preserved.
+Content only matters if Objective is still active and work is genuinely in progress.
+
+Checking before overwrite:
+- Read the file
+- If Objective matches the current task → update in place (overwrite)
+- If Objective does NOT match → overwrite the entire file with the new state
+- Never append. Never skip the update because "there's already something there".
+
 ### 4. Keep the checkpoint small
 
 `CURRENT_STATE.md` should usually stay under about 40 lines and be readable in

scripts/continuity_doctor.py

@@ -15,7 +15,7 @@ import sys
 import re
 from datetime import datetime, timezone
 from pathlib import Path
-from typing import Optional
+from typing import Dict, List, Optional, Tuple
 
 
 # ---------------------------------------------------------------------------
@@ -33,7 +33,7 @@ class Severity:
 # ---------------------------------------------------------------------------
 class DiagnosticReport:
     def __init__(self):
-        self.entries: list[tuple[str, str]] = []
+        self.entries: List[Tuple[str, str]] = []
         self._worst = Severity.OK
 
     def add(self, severity: str, message: str):
@@ -112,7 +112,7 @@ def check_staleness(state_file: Path, workspace: Path, report: DiagnosticReport)
 def check_template_compliance(state_file: Path, report: DiagnosticReport) -> dict:
     """Check all required sections are present and not placeholder-only."""
     content = state_file.read_text(encoding="utf-8")
-    sections_found: dict[str, str] = {}
+    sections_found: Dict[str, str] = {}
 
     for section in REQUIRED_SECTIONS:
         # Match ## Section or ## Section\n