fix(dashboard): v0.4 C.2.1 -- route PUT /config to multi-file save_section (Rule 17 persistence unblocked)

C.2 surfaced that GUI config saves were broken in the prod multi-file
layout. This fixes it. Pre-existing v0.3-era bug (predates C.2; affected
EVERY config section, not just environmental).

Save flow (before -> after):
  before: PUT /api/config/{section} -> config.py::load_config(config.yaml)
          [monolithic, vanilla YAML] -> blows up on the !include orchestrator
          ("could not determine a constructor for the tag '!include'"),
          then config.py::save_config (same !include-blind path). Every save
          500'd; nothing persisted.
  after:  PUT validates the body by coercing to the section dataclass (runs
          __post_init__ validators, e.g. feed_source), then persists via
          config_loader.py::save_section(section, dict, config_dir) -- the
          multi-file / !include-aware writer. It writes ONLY the section's
          target file (env_feeds.yaml for environmental, notifications.yaml,
          llm.yaml, ...), strips SECRET_FIELDS (traffic.api_key, firms.map_key)
          and extracts LOCAL_FIELDS (ducting lat/lon -> local.yaml). The
          orchestrator config.yaml and its !include directives are never
          re-parsed. Live app.state.config is kept in sync via setattr when
          the section isn't restart-required (no disk reload needed).

Also: save_section now tolerates a top-level LIST section (mesh_sources) --
it cleans each item for secrets and writes the list directly instead of
assuming a dict (which would have crashed). Other callers of save_config are
untouched (it remains valid for the monolithic single-file path).

Files: meshai/dashboard/api/config_routes.py (PUT handler + import),
meshai/config_loader.py (save_section list guard),
tests/test_dashboard_config_save.py (new).

Verification:
- (A) py_compile clean on config_routes.py + config_loader.py.
- (C) pytest -q: 272 passed (269 + 3 new -- save_section writes env_feeds,
  strips secret fields, handles the mesh_sources list section).
- (D) Rebuilt prod; ran the C.2 round-trip again, now SUCCESS: backup
  env_feeds.yaml (md5 dde5d634...), GET then PUT /api/config/environmental ->
  {"saved":true,"restart_required":false} (NO !include error); disk reflected
  it (feed_source on all 10 adapters + central block written); restored from
  backup -> md5 matches original -> DISK_PRISTINE_RESTORED.
- (E) Rule 17 round-trip confirmed: the GUI can now SAVE config that
  round-trips to disk in the multi-file !include layout, secrets staying in
  .env and local fields in local.yaml.

C.3 (quake -> central flip) is now unblocked: feed_source can be flipped and
saved from the GUI.

Follow-up (non-blocking): mesh_sources per-item secret stripping
(mesh_sources.*.api_token) isn't matched by the section-relative check in the
new list path; mesh_sources files are volume-only (not git) and this was no
worse before, but worth tightening when mesh_sources GUI save is exercised.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

meshai/dashboard/api/config_routes.py

@@ -11,6 +11,7 @@ from meshai.config import (
     load_config,
     save_config,
 )
+from meshai.config_loader import save_section, get_config_dir_from_path
 
 logger = logging.getLogger(__name__)
 
@@ -102,9 +103,6 @@ async def update_config_section(section: str, request: Request):
         raise HTTPException(status_code=422, detail=f"Invalid JSON: {e}")
 
     try:
-        # Load fresh config from file to avoid conflicts
-        config = load_config(config_path)
-
         # Get the section's dataclass type
         field_info = Config.__dataclass_fields__.get(section)
         if not field_info:
@@ -112,31 +110,39 @@ async def update_config_section(section: str, request: Request):
 
         field_type = field_info.type
 
-        # Handle list types (mesh_sources)
+        # Validate by coercing to the dataclass (runs __post_init__ validators),
+        # then persist via the multi-file / !include-aware save_section. The
+        # monolithic save_config cannot parse the !include orchestrator and blew
+        # up on every save in the prod layout (v0.4 C.2.1 fix).
         if section == "mesh_sources":
             from meshai.config import MeshSourceConfig
             new_value = [
                 _dict_to_dataclass(MeshSourceConfig, item) if isinstance(item, dict) else item
                 for item in body
             ]
-        # Handle dataclass types
+            data_to_save = [
+                _dataclass_to_dict(v) if hasattr(v, "__dataclass_fields__") else v
+                for v in new_value
+            ]
         elif hasattr(field_type, "__dataclass_fields__"):
             new_value = _dict_to_dataclass(field_type, body)
+            data_to_save = _dataclass_to_dict(new_value)
         else:
             new_value = body
+            data_to_save = body
 
-        # Set the section on config
-        setattr(config, section, new_value)
-
-        # Save config to file
-        save_config(config, config_path)
+        config_dir = get_config_dir_from_path(config_path)
+        save_section(section, data_to_save, config_dir)
 
         # Determine if restart is required
         restart_required = section in RESTART_REQUIRED_SECTIONS
 
-        # Update live config if restart not required
-        if not restart_required:
-            request.app.state.config = config
+        # Keep the live config in sync (no disk reload needed) when no restart is required
+        if not restart_required and getattr(request.app.state, "config", None) is not None:
+            try:
+                setattr(request.app.state.config, section, new_value)
+            except Exception:
+                pass
 
         logger.info(f"Config section '{section}' updated, restart_required={restart_required}")