feat(gateway): generic plugin hooks for env enablement + cron delivery

Widen the platform-plugin surface so plugins can self-configure from env
vars and opt into cron home-channel delivery without editing core files.
Closes the scope gap that forced every new platform (Google Chat, Teams,
IRC, future) to either touch gateway/config.py, cron/scheduler.py, and
hermes_cli/config.py or live without env-only setup.

Changes:

- gateway/platform_registry.py: two new optional PlatformEntry fields.
  - env_enablement_fn: () -> Optional[dict]. Called during
    _apply_env_overrides BEFORE the adapter is constructed. Returned
    dict fields are merged into PlatformConfig.extra; the special
    'home_channel' key (if present) becomes a proper HomeChannel
    dataclass on the PlatformConfig.
  - cron_deliver_env_var: name of the *_HOME_CHANNEL env var. When set,
    the plugin platform is a valid cron deliver= target and cron reads
    the env var to resolve the default chat/room ID.

- gateway/config.py: the existing plugin-platform enable pass at the
  bottom of _apply_env_overrides now calls env_enablement_fn and seeds
  extras/home_channel. No effect on plugins that don't set the new
  field.

- cron/scheduler.py: _is_known_delivery_platform and
  _resolve_home_env_var fall through to the registry when the platform
  isn't in the hardcoded built-in sets. New _iter_home_target_platforms
  helper iterates built-ins + plugin platforms for the deliver=origin
  fallback.

- gateway/run.py: _home_target_env_var now consults the new resolver so
  plugin-defined home channels work for non-cron call sites too.

- hermes_cli/config.py: new _inject_platform_plugin_env_vars() sibling
  of _inject_profile_env_vars(). Scans plugins/platforms/*/plugin.yaml
  at import time and contributes entries to OPTIONAL_ENV_VARS so
  'hermes config' UI discovers them. Supports bare-string and rich-dict
  requires_env entries plus a new optional_env list for non-required
  vars (home channels, allowlists).

All additions are strictly opt-in. Existing plugins (IRC, Teams,
image_gen, memory) see zero behavior change until they adopt the new
fields.

cron/scheduler.py

@@ -152,9 +152,54 @@ def _resolve_origin(job: dict) -> Optional[dict]:
     return None
 
 
+def _plugin_cron_env_var(platform_name: str) -> str:
+    """Return the cron home-channel env var registered by a plugin platform.
+
+    Falls through the platform registry so plugins that set
+    ``cron_deliver_env_var`` on their ``PlatformEntry`` get cron delivery
+    support without editing this module.
+    """
+    try:
+        from hermes_cli.plugins import discover_plugins
+        discover_plugins()  # idempotent
+        from gateway.platform_registry import platform_registry
+        entry = platform_registry.get(platform_name.lower())
+        if entry and entry.cron_deliver_env_var:
+            return entry.cron_deliver_env_var
+    except Exception:
+        pass
+    return ""
+
+
+def _is_known_delivery_platform(platform_name: str) -> bool:
+    """Whether ``platform_name`` is a valid cron delivery target.
+
+    Hardcoded built-ins in ``_KNOWN_DELIVERY_PLATFORMS`` are checked first;
+    plugin platforms registered via ``PlatformEntry`` are accepted if they
+    provide a ``cron_deliver_env_var``.
+    """
+    name = platform_name.lower()
+    if name in _KNOWN_DELIVERY_PLATFORMS:
+        return True
+    return bool(_plugin_cron_env_var(name))
+
+
+def _resolve_home_env_var(platform_name: str) -> str:
+    """Return the env var name for a platform's cron home channel.
+
+    Built-in platforms are in ``_HOME_TARGET_ENV_VARS``; plugin platforms are
+    resolved from the platform registry.
+    """
+    name = platform_name.lower()
+    env_var = _HOME_TARGET_ENV_VARS.get(name)
+    if env_var:
+        return env_var
+    return _plugin_cron_env_var(name)
+
+
 def _get_home_target_chat_id(platform_name: str) -> str:
     """Return the configured home target chat/room ID for a delivery platform."""
-    env_var = _HOME_TARGET_ENV_VARS.get(platform_name.lower())
+    env_var = _resolve_home_env_var(platform_name)
     if not env_var:
         return ""
     value = os.getenv(env_var, "")
@@ -167,7 +212,7 @@ def _get_home_target_chat_id(platform_name: str) -> str:
 
 def _get_home_target_thread_id(platform_name: str) -> Optional[str]:
     """Return the optional thread/topic ID for a platform home target."""
-    env_var = _HOME_TARGET_ENV_VARS.get(platform_name.lower())
+    env_var = _resolve_home_env_var(platform_name)
     if not env_var:
         return None
     value = os.getenv(f"{env_var}_THREAD_ID", "").strip()
@@ -178,6 +223,24 @@ def _get_home_target_thread_id(platform_name: str) -> Optional[str]:
     return value or None
 
 
+def _iter_home_target_platforms():
+    """Iterate built-in + plugin platform names that expose a home channel.
+
+    Used by the ``deliver=origin`` fallback when the job has no origin.
+    """
+    for name in _HOME_TARGET_ENV_VARS:
+        yield name
+    try:
+        from hermes_cli.plugins import discover_plugins
+        discover_plugins()  # idempotent
+        from gateway.platform_registry import platform_registry
+        for entry in platform_registry.plugin_entries():
+            if entry.cron_deliver_env_var and entry.name not in _HOME_TARGET_ENV_VARS:
+                yield entry.name
+    except Exception:
+        pass
+
+
 def _resolve_single_delivery_target(job: dict, deliver_value: str) -> Optional[dict]:
     """Resolve one concrete auto-delivery target for a cron job."""
 
@@ -195,7 +258,7 @@ def _resolve_single_delivery_target(job: dict, deliver_value: str) -> Optional[d
             }
         # Origin missing (e.g. job created via API/script) — try each
         # platform's home channel as a fallback instead of silently dropping.
-        for platform_name in _HOME_TARGET_ENV_VARS:
+        for platform_name in _iter_home_target_platforms():
             chat_id = _get_home_target_chat_id(platform_name)
             if chat_id:
                 logger.info(
@@ -251,7 +314,7 @@ def _resolve_single_delivery_target(job: dict, deliver_value: str) -> Optional[d
             "thread_id": origin.get("thread_id"),
         }
 
-    if platform_name.lower() not in _KNOWN_DELIVERY_PLATFORMS:
+    if not _is_known_delivery_platform(platform_name):
         return None
     chat_id = _get_home_target_chat_id(platform_name)
     if not chat_id:

gateway/config.py

@@ -1664,7 +1664,10 @@ def _apply_env_overrides(config: GatewayConfig) -> None:
     # Registry-driven enable for plugin platforms.  Built-ins have explicit
     # blocks above; plugins expose check_fn() which is the single source of
     # truth for "are my env vars set?".  When it returns True, ensure the
-    # platform is enabled so start() will create its adapter.
+    # platform is enabled so start() will create its adapter.  Plugins that
+    # need to seed ``PlatformConfig.extra`` from env vars (e.g. Google Chat's
+    # project_id / subscription_name) can supply ``env_enablement_fn`` on
+    # their PlatformEntry — called here BEFORE adapter construction.
     try:
         from hermes_cli.plugins import discover_plugins
         discover_plugins()  # idempotent
@@ -1680,5 +1683,31 @@ def _apply_env_overrides(config: GatewayConfig) -> None:
             if platform not in config.platforms:
                 config.platforms[platform] = PlatformConfig()
             config.platforms[platform].enabled = True
+            # Seed extras from env if the plugin opted in.
+            if entry.env_enablement_fn is not None:
+                try:
+                    seed = entry.env_enablement_fn()
+                except Exception as e:
+                    logger.debug(
+                        "env_enablement_fn for %s raised: %s", entry.name, e
+                    )
+                    seed = None
+                if isinstance(seed, dict) and seed:
+                    # Extract the home_channel dict (if provided) so we wire it
+                    # up as a proper HomeChannel dataclass.  Everything else is
+                    # merged into ``extra``.
+                    home = seed.pop("home_channel", None)
+                    config.platforms[platform].extra.update(seed)
+                    if isinstance(home, dict) and home.get("chat_id"):
+                        config.platforms[platform].home_channel = HomeChannel(
+                            platform=platform,
+                            chat_id=str(home["chat_id"]),
+                            name=str(home.get("name") or "Home"),
+                            thread_id=(
+                                str(home["thread_id"])
+                                if home.get("thread_id")
+                                else None
+                            ),
+                        )
     except Exception as e:
         logger.debug("Plugin platform enable pass failed: %s", e)

gateway/platform_registry.py

@@ -110,6 +110,21 @@ class PlatformEntry:
     # Do not use markdown.").  Empty string = no hint.
     platform_hint: str = ""
 
+    # ── Env-driven auto-configuration ──
+    # Optional: read env vars, return a dict of ``PlatformConfig.extra`` fields
+    # to seed when the platform is auto-enabled.  Called during
+    # ``_apply_env_overrides`` BEFORE the adapter is constructed, so
+    # ``gateway status`` etc. can reflect env-only configuration without
+    # instantiating the adapter.  Return ``None`` (or an empty dict) to skip.
+    # Signature: () -> Optional[dict[str, Any]]
+    env_enablement_fn: Optional[Callable[[], Optional[dict]]] = None
+
+    # Optional: home-channel env var name for cron/notification delivery
+    # (e.g. ``"IRC_HOME_CHANNEL"``).  When set, ``cron.scheduler`` treats this
+    # platform as a valid ``deliver=<name>`` target and reads the env var to
+    # resolve the default chat/room ID.  Empty = no cron home-channel support.
+    cron_deliver_env_var: str = ""
+
 
 class PlatformRegistry:
     """Central registry of platform adapters.

gateway/run.py

@@ -258,13 +258,18 @@ def _ensure_ssl_certs() -> None:
             return
 
 def _home_target_env_var(platform_name: str) -> str:
-    """Return the configured home-target env var for a platform."""
+    """Return the configured home-target env var for a platform.
-    from cron.scheduler import _HOME_TARGET_ENV_VARS
 
-    return _HOME_TARGET_ENV_VARS.get(
+    Consults built-in ``_HOME_TARGET_ENV_VARS`` first, then the plugin
-        platform_name.lower(),
+    registry via ``cron.scheduler._resolve_home_env_var``, then falls back
-        f"{platform_name.upper()}_HOME_CHANNEL",
+    to ``<PLATFORM>_HOME_CHANNEL`` for unknown names.
-    )
+    """
+    from cron.scheduler import _resolve_home_env_var
+
+    resolved = _resolve_home_env_var(platform_name)
+    if resolved:
+        return resolved
+    return f"{platform_name.upper()}_HOME_CHANNEL"
 
 
 def _home_thread_env_var(platform_name: str) -> str:

hermes_cli/config.py

@@ -4961,3 +4961,100 @@ def _inject_profile_env_vars() -> None:
 
 # Eagerly inject so that OPTIONAL_ENV_VARS is fully populated at import time.
 _inject_profile_env_vars()
+
+
+# ── Platform-plugin env var injection ────────────────────────────────────────
+# Bundled platform plugins under ``plugins/platforms/*/plugin.yaml`` declare
+# their required env vars via ``requires_env``.  This mirror of
+# ``_inject_profile_env_vars`` surfaces them in ``hermes config`` UI so users
+# can configure Teams / IRC / Google Chat without the core repo ever needing
+# to know they exist.
+#
+# Each ``requires_env`` entry may be a bare string (name only) or a dict:
+#
+#   requires_env:
+#     - TEAMS_CLIENT_ID                          # minimal
+#     - name: TEAMS_CLIENT_SECRET                # rich
+#       description: "Teams bot client secret"
+#       url: "https://portal.azure.com/"
+#       password: true
+#       prompt: "Teams client secret"
+#
+# An optional ``optional_env`` block surfaces non-required vars the same way
+# (e.g. allowlist, home channel).
+
+_platform_plugin_env_vars_injected = False
+
+
+def _inject_platform_plugin_env_vars() -> None:
+    """Populate OPTIONAL_ENV_VARS from bundled platform plugin manifests.
+
+    Called once at module load time. Idempotent — repeated calls are no-ops.
+    Failures are swallowed so a malformed plugin.yaml can't break CLI import.
+    """
+    global _platform_plugin_env_vars_injected
+    if _platform_plugin_env_vars_injected:
+        return
+    _platform_plugin_env_vars_injected = True
+    try:
+        import yaml  # type: ignore
+
+        # Resolve the bundled plugins dir from this file's location so the
+        # injector works regardless of CWD.
+        repo_root = Path(__file__).resolve().parents[1]
+        platforms_dir = repo_root / "plugins" / "platforms"
+        if not platforms_dir.is_dir():
+            return
+        for child in platforms_dir.iterdir():
+            if not child.is_dir():
+                continue
+            manifest_path = child / "plugin.yaml"
+            if not manifest_path.exists():
+                manifest_path = child / "plugin.yml"
+            if not manifest_path.exists():
+                continue
+            try:
+                with open(manifest_path, "r", encoding="utf-8") as f:
+                    manifest = yaml.safe_load(f) or {}
+            except Exception:
+                continue
+            label = manifest.get("label") or manifest.get("name") or child.name
+            # Merge required + optional env var declarations.
+            entries = list(manifest.get("requires_env") or [])
+            entries.extend(manifest.get("optional_env") or [])
+            for entry in entries:
+                if isinstance(entry, str):
+                    name = entry
+                    meta: dict = {}
+                elif isinstance(entry, dict) and entry.get("name"):
+                    name = entry["name"]
+                    meta = entry
+                else:
+                    continue
+                if name in OPTIONAL_ENV_VARS:
+                    continue  # hardcoded entry wins (back-compat)
+                # Heuristic: anything named *TOKEN, *SECRET, *KEY, *PASSWORD
+                # is a password field unless explicitly overridden.
+                name_upper = name.upper()
+                is_secret = bool(meta.get("password") or meta.get("secret"))
+                if not is_secret and not meta.get("password") is False:
+                    is_secret = any(
+                        name_upper.endswith(suf)
+                        for suf in ("_TOKEN", "_SECRET", "_KEY", "_PASSWORD", "_JSON")
+                    )
+                OPTIONAL_ENV_VARS[name] = {
+                    "description": (
+                        meta.get("description")
+                        or f"{label} configuration"
+                    ),
+                    "prompt": meta.get("prompt") or name,
+                    "url": meta.get("url") or None,
+                    "password": is_secret,
+                    "category": meta.get("category") or "messaging",
+                }
+    except Exception:
+        pass
+
+
+# Eagerly inject so that platform plugin env vars show up in the setup wizard.
+_inject_platform_plugin_env_vars()