township: loading a template persists, not just applies

Loading applied the template to the live session but never wrote the active config file,
which made "switch live" only half true:

- the launcher starts the tool with --config <out_dir>/township_config.json, so the
  template silently reverted on the next restart;
- _ref_gen_res_steps deliberately RE-READS that file from disk for keyframe_size and
  keyframe_steps (so Run-page edits apply without a restart), which meant those two
  options came from the stale file even in the same session — the loaded template
  disagreeing with itself.

The load now writes the active config too, reports the path back as `persisted`, and says
so in the log if the write fails rather than leaving a switch that looks applied and
reverts later.

Verified live: save a template with keyframe_size 1024x576, load it, and the active
config file on disk carries it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0182DhR1eFNPQyGmDrpHbedY

tests/test_township_templates.py

@@ -192,6 +192,23 @@ def test_the_web_routes_exist(route):
     assert route in SRC
 
 
+def test_loading_persists_to_the_active_config():
+    """Live is not enough. The launcher starts the tool with
+    --config <out_dir>/township_config.json, so a load that only changed the session
+    would silently revert on the next restart — and _ref_gen_res_steps RE-READS that
+    file for keyframe_size/keyframe_steps, so a stale file makes those two options
+    disagree with the rest of the loaded template in the same session."""
+    seg = SRC[SRC.index('if path in ("/templates/load"'):SRC.index('if path == "/process":')]
+    assert "township_config.json" in seg
+    assert 'open(_ap, "w"' in seg
+    assert '"persisted"' in seg
+
+
+def test_a_failed_persist_is_reported_not_swallowed():
+    seg = SRC[SRC.index('if path in ("/templates/load"'):SRC.index('if path == "/process":')]
+    assert "could not write" in seg
+
+
 def test_loading_applies_to_the_live_session():
     """The Run page renders from default_args, so a load that only wrote a file would
     appear to do nothing until restart."""

tools/gen_township_fighters.py

@@ -11042,9 +11042,34 @@ async function resetPrompts(ev){
                 # reload and every subsequent job uses it.
                 for _k, _val in tcfg.items():
                     setattr(default_args, _k, _val)
-                _web_log(f"  ⚙ Loaded template '{nm}' ({len(tcfg)} options)")
+                # …and make it STICK, by writing the active config file too. Two reasons
+                # this is not optional:
+                #   1. the launcher starts the tool with --config <out_dir>/
+                #      township_config.json, so without this the template silently
+                #      reverts on the next restart;
+                #   2. _ref_gen_res_steps deliberately RE-READS that file from disk for
+                #      keyframe_size/keyframe_steps, so leaving it stale would have those
+                #      two options disagree with the rest of the loaded template in the
+                #      very same session.
+                _active = (getattr(default_args, "config", None)
+                           or str(Path(default_args.out_dir) / "township_config.json"))
+                _persisted = None
+                try:
+                    _ap = Path(_active)
+                    _ap.parent.mkdir(parents=True, exist_ok=True)
+                    with open(_ap, "w", encoding="utf-8") as f:
+                        _j.dump(tcfg, f, indent=2, sort_keys=True)
+                        f.write("\n")
+                    _persisted = str(_ap)
+                except Exception as e:
+                    # The switch is already live; failing to persist is worth saying
+                    # out loud rather than silently reverting on the next restart.
+                    _web_log(f"  ⚠ Loaded '{nm}' live, but could not write {_active}: {e}")
+                _web_log(f"  ⚙ Loaded template '{nm}' ({len(tcfg)} options)"
+                         + (f" → {_persisted}" if _persisted else ""))
                 self._send(200, "application/json",
-                           _j.dumps({"ok": True, "name": nm, "options": len(tcfg)}))
+                           _j.dumps({"ok": True, "name": nm, "options": len(tcfg),
+                                     "persisted": _persisted}))
                 return
 
             if path == "/process":