diff --git a/README.md b/README.md
index 7c64ec6c5..54790510c 100644
--- a/README.md
+++ b/README.md
@@ -343,7 +343,7 @@ See the [MCP Server Guide](backend/docs/MCP_SERVER.md) for detailed instructions
 
 DeerFlow supports receiving tasks from messaging apps. Channels auto-start when configured — no public IP required for any of them.
 
-DeerFlow can also expose user-owned IM channel connections in the workspace UI. When `channel_connections` is enabled, logged-in users can connect Telegram, Slack, or Discord from the sidebar / Settings > Channels. Provider credentials are encrypted at rest, and incoming IM messages run under the connected DeerFlow user account. See [IM Channel Connections](backend/docs/IM_CHANNEL_CONNECTIONS.md) for OAuth callback URLs, webhook setup, and security notes.
+DeerFlow can also expose user-owned IM channel connections in the workspace UI. When `channel_connections` is enabled, logged-in users can connect Telegram, Slack, or Discord from the sidebar / Settings > Channels. Stored provider OAuth credentials are encrypted at rest when a provider needs them, and incoming IM messages run under the connected DeerFlow user account. See [IM Channel Connections](backend/docs/IM_CHANNEL_CONNECTIONS.md) for local/private mode, OAuth callback URLs, webhook setup, and security notes.
 
 | Channel | Transport | Difficulty |
 |---------|-----------|------------|
diff --git a/backend/CLAUDE.md b/backend/CLAUDE.md
index 73a1567a6..590c203ae 100644
--- a/backend/CLAUDE.md
+++ b/backend/CLAUDE.md
@@ -402,7 +402,9 @@ Bridges external messaging platforms (Feishu, Slack, Telegram, Discord, DingTalk
 - Per-channel configs: `feishu` (app_id, app_secret), `slack` (bot_token, app_token), `telegram` (bot_token), `dingtalk` (client_id, client_secret, optional `card_template_id` for AI Card streaming)
 
 **User-owned channel connections** (`config.yaml` -> `channel_connections`):
-- Disabled by default. When enabled, `public_base_url` and `encryption_key` are required.
+- Disabled by default. `mode: local` is the default for local/private deployments; `mode: public` requires `public_base_url`.
+- `public_base_url` is only required for provider-to-server public callbacks/webhooks such as Slack HTTP Events and Telegram webhooks. If it is omitted, OAuth redirect URLs fall back to the current request origin for localhost/private testing.
+- `encryption_key` is required before storing provider OAuth credentials for Slack and Discord. Telegram deep-link binding can run without it because it stores only connection identity/state, not per-user provider tokens.
 - Frontend APIs: `GET /api/channels/providers`, `GET /api/channels/connections`, `POST /api/channels/{provider}/connect`, and `DELETE /api/channels/connections/{connection_id}`.
 - Public provider routes: Slack/Discord OAuth callbacks and Slack/Telegram webhooks are explicitly allowed through AuthMiddleware; webhooks are exempt from CSRF because they are provider-to-server calls and validate Slack signatures or Telegram secret tokens.
 - Slack HTTP Events mode uses per-connection encrypted bot tokens for replies. Legacy Slack Socket Mode remains available through the `channels.slack` config.
diff --git a/backend/app/channels/service.py b/backend/app/channels/service.py
index 5e95b48f0..97886bfc0 100644
--- a/backend/app/channels/service.py
+++ b/backend/app/channels/service.py
@@ -85,8 +85,6 @@ def _make_connection_repo(app_config: AppConfig):
     if connection_config is None or not getattr(connection_config, "enabled", False):
         return None
     encryption_key = getattr(connection_config, "encryption_key", "")
-    if not encryption_key:
-        return None
 
     try:
         from deerflow.persistence.channel_connections import ChannelConnectionRepository, ChannelCredentialCipher
@@ -99,7 +97,8 @@ def _make_connection_repo(app_config: AppConfig):
     if session_factory is None:
         logger.warning("Channel connections are enabled but database persistence is not available")
         return None
-    return ChannelConnectionRepository(session_factory, cipher=ChannelCredentialCipher.from_key(encryption_key))
+    cipher = ChannelCredentialCipher.from_key(encryption_key) if encryption_key else None
+    return ChannelConnectionRepository(session_factory, cipher=cipher)
 
 
 class ChannelService:
diff --git a/backend/app/gateway/routers/channel_connections.py b/backend/app/gateway/routers/channel_connections.py
index e0b70defc..7bd35de0d 100644
--- a/backend/app/gateway/routers/channel_connections.py
+++ b/backend/app/gateway/routers/channel_connections.py
@@ -29,6 +29,8 @@ class ChannelProviderResponse(BaseModel):
     display_name: str
     enabled: bool
     configured: bool
+    connectable: bool
+    unavailable_reason: str | None = None
     auth_mode: str
     connection_status: str
 
@@ -93,10 +95,9 @@ def _get_repository(request: Request, config: ChannelConnectionsConfig) -> Chann
     sf = get_session_factory()
     if sf is None:
         raise HTTPException(status_code=503, detail="Channel connection persistence is not available")
-    if not config.encryption_key:
-        raise HTTPException(status_code=503, detail="Channel connection encryption key is not configured")
 
-    repo = ChannelConnectionRepository(sf, cipher=ChannelCredentialCipher.from_key(config.encryption_key))
+    cipher = ChannelCredentialCipher.from_key(config.encryption_key) if config.encryption_key else None
+    repo = ChannelConnectionRepository(sf, cipher=cipher)
     request.app.state.channel_connection_repo = repo
     return repo
 
@@ -108,6 +109,43 @@ def _provider_config(config: ChannelConnectionsConfig, provider: str):
     return provider_config
 
 
+def _provider_unavailable_reason(config: ChannelConnectionsConfig, provider: str) -> str | None:
+    provider_config = _provider_config(config, provider)
+    if not provider_config.enabled or not provider_config.configured:
+        return None
+
+    if provider == "telegram" and getattr(provider_config, "delivery", "polling") == "webhook":
+        if not provider_config.webhook_secret:
+            return "Telegram webhook delivery requires channel_connections.telegram.webhook_secret"
+        if not config.public_base_url:
+            return "Telegram webhook delivery requires channel_connections.public_base_url; use polling for local/private deployments"
+
+    if provider == "slack" and getattr(provider_config, "event_delivery", "http") == "http" and not config.public_base_url:
+        return "Slack HTTP Events require channel_connections.public_base_url; use a public URL/tunnel or Slack Socket Mode for private deployments"
+
+    if provider in {"slack", "discord"} and not config.encryption_key:
+        display_name = _PROVIDER_META[provider]["display_name"]
+        return f"{display_name} connections require channel_connections.encryption_key to store OAuth credentials"
+
+    return None
+
+
+def _require_provider_connectable(config: ChannelConnectionsConfig, provider: str) -> None:
+    reason = _provider_unavailable_reason(config, provider)
+    if reason:
+        raise HTTPException(status_code=400, detail=reason)
+
+
+def _callback_base_url(config: ChannelConnectionsConfig, request: Request) -> str:
+    if config.public_base_url:
+        return config.public_base_url.rstrip("/")
+    return str(request.base_url).rstrip("/")
+
+
+def _callback_redirect_uri(config: ChannelConnectionsConfig, request: Request, provider: str) -> str:
+    return f"{_callback_base_url(config, request)}/api/channels/{provider}/callback"
+
+
 async def _create_state(
     repo: ChannelConnectionRepository,
     *,
@@ -128,12 +166,12 @@ async def _create_state(
     return state
 
 
-def _build_connect_url(config: ChannelConnectionsConfig, provider: str, state: str) -> str:
+def _build_connect_url(config: ChannelConnectionsConfig, request: Request, provider: str, state: str) -> str:
     provider_config = _provider_config(config, provider)
     if provider == "telegram":
         return f"https://t.me/{provider_config.bot_username}?start={state}"
 
-    redirect_uri = f"{config.public_base_url.rstrip('/')}/api/channels/{provider}/callback"
+    redirect_uri = _callback_redirect_uri(config, request, provider)
     if provider == "slack":
         query = urlencode(
             {
@@ -242,7 +280,13 @@ async def _publish_slack_event(
 @router.get("/providers", response_model=ChannelProvidersResponse)
 async def get_channel_providers(request: Request) -> ChannelProvidersResponse:
     config = _get_channel_connections_config(request)
-    repo = _get_repository(request, config) if config.enabled and config.encryption_key else None
+    repo = None
+    if config.enabled:
+        try:
+            repo = _get_repository(request, config)
+        except HTTPException as exc:
+            if exc.status_code != 503:
+                raise
     owner_user_id = _get_user_id(request)
     connections = await repo.list_connections(owner_user_id) if repo is not None else []
     by_provider = {item["provider"]: item for item in connections}
@@ -251,12 +295,15 @@ async def get_channel_providers(request: Request) -> ChannelProvidersResponse:
     for provider, meta in _PROVIDER_META.items():
         status = config.provider_status(provider)
         connection = by_provider.get(provider)
+        unavailable_reason = _provider_unavailable_reason(config, provider)
         providers.append(
             ChannelProviderResponse(
                 provider=provider,
                 display_name=meta["display_name"],
                 enabled=status["enabled"],
                 configured=status["configured"],
+                connectable=status["enabled"] and status["configured"] and unavailable_reason is None,
+                unavailable_reason=unavailable_reason,
                 auth_mode=meta["auth_mode"],
                 connection_status=connection["status"] if connection else "not_connected",
             )
@@ -307,7 +354,7 @@ async def slack_oauth_callback(request: Request, code: str | None = None, state:
     if state_data is None:
         raise HTTPException(status_code=400, detail="Invalid or expired OAuth state")
 
-    redirect_uri = f"{config.public_base_url.rstrip('/')}/api/channels/slack/callback"
+    redirect_uri = _callback_redirect_uri(config, request, "slack")
     install = await slack_connect.exchange_slack_oauth_code(
         client_id=provider_config.client_id,
         client_secret=provider_config.client_secret,
@@ -351,7 +398,7 @@ async def discord_oauth_callback(request: Request, code: str | None = None, stat
     if state_data is None:
         raise HTTPException(status_code=400, detail="Invalid or expired OAuth state")
 
-    redirect_uri = f"{config.public_base_url.rstrip('/')}/api/channels/discord/callback"
+    redirect_uri = _callback_redirect_uri(config, request, "discord")
     identity = await discord_connect.complete_discord_oauth(
         client_id=provider_config.client_id,
         client_secret=provider_config.client_secret,
@@ -471,6 +518,7 @@ async def connect_channel_provider(provider: str, request: Request) -> ChannelCo
     provider_config = _provider_config(config, provider)
     if not provider_config.enabled or not provider_config.configured:
         raise HTTPException(status_code=400, detail="Channel provider is not configured")
+    _require_provider_connectable(config, provider)
 
     repo = _get_repository(request, config)
     state = await _create_state(
@@ -482,6 +530,6 @@ async def connect_channel_provider(provider: str, request: Request) -> ChannelCo
     return ChannelConnectResponse(
         provider=provider,
         mode=_PROVIDER_META[provider]["auth_mode"],
-        url=_build_connect_url(config, provider, state),
+        url=_build_connect_url(config, request, provider, state),
         expires_in=_STATE_TTL_SECONDS,
     )
diff --git a/backend/docs/IM_CHANNEL_CONNECTIONS.md b/backend/docs/IM_CHANNEL_CONNECTIONS.md
index 313b8f40c..ed3bdb63f 100644
--- a/backend/docs/IM_CHANNEL_CONNECTIONS.md
+++ b/backend/docs/IM_CHANNEL_CONNECTIONS.md
@@ -6,9 +6,27 @@ DeerFlow supports user-owned IM channel connections for Telegram, Slack, and Dis
 
 Enable the top-level `channel_connections` block in `config.yaml`:
 
+Local/private deployment:
+
 ```yaml
 channel_connections:
   enabled: true
+  mode: local
+
+  telegram:
+    enabled: true
+    bot_token: $TELEGRAM_BOT_TOKEN
+    bot_username: $TELEGRAM_BOT_USERNAME
+```
+
+This mode is intended for a DeerFlow instance running on a developer machine or a private network. Telegram uses the existing long-polling worker, so it does not need a public URL. The frontend `Connect` button returns a Telegram deep link and stores a one-time state locally so the `/start` message can bind the Telegram chat to the current DeerFlow user.
+
+Public deployment:
+
+```yaml
+channel_connections:
+  enabled: true
+  mode: public
   public_base_url: https://deerflow.example.com
   encryption_key: $DEER_FLOW_CHANNEL_CONNECTIONS_KEY
 
@@ -33,7 +51,9 @@ channel_connections:
     permissions: "274877975552"
 ```
 
-`public_base_url` must be the externally reachable HTTPS origin used by provider callbacks and webhooks. `encryption_key` encrypts provider tokens at rest with Fernet. Keep it stable; v1 does not support transparent key rotation, so changing it requires users to reconnect.
+`public_base_url` is only required for public callback/webhook deployments. If it is omitted, OAuth redirect URLs are built from the current request origin, which is suitable for localhost development when the provider allows an exact localhost redirect URI. Provider-to-server webhooks such as Slack HTTP Events and Telegram webhooks still need a reachable public URL or a tunnel.
+
+`encryption_key` encrypts provider tokens at rest with Fernet. Telegram deep-link binding does not store user provider tokens, so it can run locally without this key. Slack and Discord connections store OAuth credentials and require a stable key; v1 does not support transparent key rotation, so changing it requires users to reconnect.
 
 ## Frontend Flow
 
@@ -44,10 +64,10 @@ The workspace sidebar shows a Channels group with Telegram, Slack, and Discord.
 Telegram:
 
 - Register a bot with BotFather.
-- Configure the bot username, bot token, and a random webhook secret.
+- Configure the bot username and bot token.
 - Users connect with a deep link: `https://t.me/<bot_username>?start=<state>`.
-- Production webhook path: `POST /api/channels/webhooks/telegram`, protected by `X-Telegram-Bot-Api-Secret-Token`.
-- Local/self-hosted long polling still works through the existing Telegram channel worker.
+- Local/private delivery uses the existing long-polling channel worker and does not require `public_base_url`.
+- Production webhook path: `POST /api/channels/webhooks/telegram`, protected by `X-Telegram-Bot-Api-Secret-Token`; webhook delivery requires `webhook_secret` and a public `public_base_url`.
 
 Slack:
 
@@ -57,11 +77,12 @@ Slack:
 - Required signing secret: Slack's request signing secret, not the deprecated verification token.
 - Suggested MVP bot scopes: `app_mentions:read`, `chat:write`, `channels:history`, `channels:read`.
 - Slack events are signature-verified, deduplicated by `event_id`, and then routed to a matching user connection.
+- In local/private mode, Slack HTTP Events are reported as unavailable unless `public_base_url` is set to a tunnel or public HTTPS URL.
 
 Discord:
 
 - Create a Discord application and bot.
-- Redirect URL: `https://<public_base_url>/api/channels/discord/callback`.
+- Redirect URL: `https://<public_base_url>/api/channels/discord/callback` in public mode, or the matching localhost callback URL in local development if the Discord application is configured to allow it.
 - DeerFlow starts OAuth with `identify guilds bot applications.commands` and the configured bot permissions.
 - The Discord Gateway is still handled by `discord.py`; message content may require the privileged Message Content Intent depending on your bot setup.
 
diff --git a/backend/packages/harness/deerflow/config/channel_connections_config.py b/backend/packages/harness/deerflow/config/channel_connections_config.py
index bca41838b..0de625340 100644
--- a/backend/packages/harness/deerflow/config/channel_connections_config.py
+++ b/backend/packages/harness/deerflow/config/channel_connections_config.py
@@ -2,8 +2,13 @@
 
 from __future__ import annotations
 
+from typing import Literal
+
 from pydantic import BaseModel, Field, model_validator
 
+ChannelConnectionMode = Literal["local", "private", "public"]
+TelegramDeliveryMode = Literal["polling", "webhook"]
+
 
 class SlackChannelConnectionConfig(BaseModel):
     enabled: bool = False
@@ -29,13 +34,16 @@ class TelegramChannelConnectionConfig(BaseModel):
     enabled: bool = False
     bot_token: str = ""
     bot_username: str = ""
+    delivery: TelegramDeliveryMode = "polling"
     webhook_secret: str = ""
     oidc_client_id: str = ""
     oidc_client_secret: str = ""
 
     @property
     def configured(self) -> bool:
-        return bool(self.bot_token and self.bot_username and self.webhook_secret)
+        if self.delivery == "webhook":
+            return bool(self.bot_token and self.bot_username and self.webhook_secret)
+        return bool(self.bot_token and self.bot_username)
 
 
 class DiscordChannelConnectionConfig(BaseModel):
@@ -55,6 +63,7 @@ class ChannelConnectionsConfig(BaseModel):
     """Top-level config for browser-connectable IM channels."""
 
     enabled: bool = False
+    mode: ChannelConnectionMode = "local"
     public_base_url: str = ""
     encryption_key: str = ""
     slack: SlackChannelConnectionConfig = Field(default_factory=SlackChannelConnectionConfig)
@@ -64,10 +73,8 @@ class ChannelConnectionsConfig(BaseModel):
     @model_validator(mode="after")
     def _require_shared_config_when_enabled(self) -> ChannelConnectionsConfig:
         missing: list[str] = []
-        if self.enabled and not self.public_base_url:
-            missing.append("public_base_url is required when channel_connections.enabled is true")
-        if self.enabled and not self.encryption_key:
-            missing.append("encryption_key is required when channel_connections.enabled is true")
+        if self.enabled and self.mode == "public" and not self.public_base_url:
+            missing.append("public_base_url is required when channel_connections.mode is public")
         if missing:
             raise ValueError("; ".join(missing))
         return self
diff --git a/backend/packages/harness/deerflow/persistence/channel_connections/sql.py b/backend/packages/harness/deerflow/persistence/channel_connections/sql.py
index 60f12f6aa..6f4924c7b 100644
--- a/backend/packages/harness/deerflow/persistence/channel_connections/sql.py
+++ b/backend/packages/harness/deerflow/persistence/channel_connections/sql.py
@@ -53,7 +53,7 @@ class ChannelConnectionRepository:
         self,
         session_factory: async_sessionmaker[AsyncSession],
         *,
-        cipher: ChannelCredentialCipher,
+        cipher: ChannelCredentialCipher | None = None,
     ) -> None:
         self.session_factory = session_factory
         self._cipher = cipher
@@ -77,6 +77,13 @@ class ChannelConnectionRepository:
             return value
         return value.replace(tzinfo=UTC)
 
+    def _encrypt_optional_secret(self, value: str | None) -> str | None:
+        if value is None:
+            return None
+        if self._cipher is None:
+            raise RuntimeError("channel connection encryption key is required")
+        return self._cipher.encrypt_text(value)
+
     @staticmethod
     def _connection_to_dict(row: ChannelConnectionRow) -> dict[str, Any]:
         data = row.to_dict()
@@ -166,6 +173,8 @@ class ChannelConnectionRepository:
         refresh_expires_at: datetime | None = None,
         extra: dict[str, Any] | None = None,
     ) -> None:
+        if self._cipher is None:
+            raise RuntimeError("channel connection encryption key is required")
         async with self.session_factory() as session:
             row = await session.get(ChannelCredentialRow, connection_id)
             if row is None:
@@ -181,6 +190,8 @@ class ChannelConnectionRepository:
             await session.commit()
 
     async def get_credentials(self, connection_id: str) -> dict[str, Any] | None:
+        if self._cipher is None:
+            return None
         async with self.session_factory() as session:
             row = await session.get(ChannelCredentialRow, connection_id)
             if row is None:
@@ -217,7 +228,7 @@ class ChannelConnectionRepository:
             state_hash=self.hash_state(state),
             owner_user_id=owner_user_id,
             provider=provider,
-            code_verifier_encrypted=self._cipher.encrypt_text(code_verifier),
+            code_verifier_encrypted=self._encrypt_optional_secret(code_verifier),
             nonce_hash=nonce_hash,
             redirect_after=redirect_after,
             requested_scopes_json=list(requested_scopes or []),
diff --git a/backend/tests/test_channel_connections_config.py b/backend/tests/test_channel_connections_config.py
index f2bffd1e1..370282474 100644
--- a/backend/tests/test_channel_connections_config.py
+++ b/backend/tests/test_channel_connections_config.py
@@ -17,13 +17,35 @@ def test_channel_connections_disabled_by_default():
     assert config.discord.enabled is False
 
 
-def test_enabled_channel_connections_require_public_url_and_encryption_key():
-    with pytest.raises(ValidationError) as excinfo:
-        ChannelConnectionsConfig(enabled=True)
+def test_enabled_channel_connections_can_run_in_local_mode_without_public_url_or_encryption_key():
+    config = ChannelConnectionsConfig.model_validate(
+        {
+            "enabled": True,
+            "mode": "local",
+            "telegram": {
+                "enabled": True,
+                "bot_token": "telegram-token",
+                "bot_username": "deerflow_bot",
+            },
+        }
+    )
 
-    message = str(excinfo.value)
-    assert "public_base_url is required" in message
-    assert "encryption_key is required" in message
+    assert config.public_base_url == ""
+    assert config.encryption_key == ""
+    assert config.provider_status("telegram") == {"enabled": True, "configured": True}
+
+
+def test_public_mode_requires_public_url():
+    with pytest.raises(ValidationError) as excinfo:
+        ChannelConnectionsConfig.model_validate(
+            {
+                "enabled": True,
+                "mode": "public",
+                "encryption_key": "test-secret",
+            }
+        )
+
+    assert "public_base_url is required when channel_connections.mode is public" in str(excinfo.value)
 
 
 def test_provider_config_completeness_is_reported_without_crashing():
diff --git a/backend/tests/test_channel_connections_router.py b/backend/tests/test_channel_connections_router.py
index a8c73d28e..1b7e8cb0e 100644
--- a/backend/tests/test_channel_connections_router.py
+++ b/backend/tests/test_channel_connections_router.py
@@ -25,15 +25,13 @@ def _user() -> User:
     )
 
 
-async def _make_repo(tmp_path):
+async def _make_repo(tmp_path, encryption_key: str | None = "router-secret"):
     from deerflow.persistence.channel_connections import ChannelConnectionRepository, ChannelCredentialCipher
     from deerflow.persistence.engine import get_session_factory, init_engine
 
     await init_engine("sqlite", url=f"sqlite+aiosqlite:///{tmp_path / 'router.db'}", sqlite_dir=str(tmp_path))
-    return ChannelConnectionRepository(
-        get_session_factory(),
-        cipher=ChannelCredentialCipher.from_key("router-secret"),
-    )
+    cipher = ChannelCredentialCipher.from_key(encryption_key) if encryption_key else None
+    return ChannelConnectionRepository(get_session_factory(), cipher=cipher)
 
 
 def _make_app(config: ChannelConnectionsConfig, repo):
@@ -164,6 +162,74 @@ def test_connect_telegram_returns_deep_link_and_persists_state(tmp_path):
     anyio.run(repo.close)
 
 
+def test_connect_telegram_local_mode_without_public_url_or_encryption_key(tmp_path):
+    import anyio
+
+    repo = anyio.run(_make_repo, tmp_path, None)
+    app = _make_app(
+        ChannelConnectionsConfig.model_validate(
+            {
+                "enabled": True,
+                "mode": "local",
+                "telegram": {
+                    "enabled": True,
+                    "bot_token": "telegram-token",
+                    "bot_username": "deerflow_bot",
+                },
+            }
+        ),
+        repo,
+    )
+
+    with TestClient(app) as client:
+        response = client.post("/api/channels/telegram/connect")
+
+    assert response.status_code == 200
+    body = response.json()
+    assert body["provider"] == "telegram"
+    assert body["url"].startswith("https://t.me/deerflow_bot?start=")
+
+    async def count_states():
+        return await repo.count_oauth_states(owner_user_id=str(_user().id), provider="telegram")
+
+    assert anyio.run(count_states) == 1
+
+    anyio.run(repo.close)
+
+
+def test_get_providers_reports_slack_http_unavailable_without_public_url(tmp_path):
+    import anyio
+
+    repo = anyio.run(_make_repo, tmp_path)
+    config = ChannelConnectionsConfig.model_validate(
+        {
+            "enabled": True,
+            "mode": "local",
+            "encryption_key": "router-secret",
+            "slack": {
+                "enabled": True,
+                "client_id": "slack-client",
+                "client_secret": "slack-secret",
+                "signing_secret": "slack-signing-secret",
+                "event_delivery": "http",
+            },
+        }
+    )
+    app = _make_app(config, repo)
+
+    with TestClient(app) as client:
+        response = client.get("/api/channels/providers")
+
+    assert response.status_code == 200
+    slack = next(item for item in response.json()["providers"] if item["provider"] == "slack")
+    assert slack["enabled"] is True
+    assert slack["configured"] is True
+    assert slack["connectable"] is False
+    assert "public_base_url" in slack["unavailable_reason"]
+
+    anyio.run(repo.close)
+
+
 def test_connect_unconfigured_provider_returns_400(tmp_path):
     import anyio
 
@@ -189,6 +255,99 @@ def test_connect_unconfigured_provider_returns_400(tmp_path):
     anyio.run(repo.close)
 
 
+def test_connect_slack_http_without_public_url_returns_400(tmp_path):
+    import anyio
+
+    repo = anyio.run(_make_repo, tmp_path)
+    app = _make_app(
+        ChannelConnectionsConfig.model_validate(
+            {
+                "enabled": True,
+                "mode": "local",
+                "encryption_key": "router-secret",
+                "slack": {
+                    "enabled": True,
+                    "client_id": "slack-client",
+                    "client_secret": "slack-secret",
+                    "signing_secret": "slack-signing-secret",
+                    "event_delivery": "http",
+                },
+            }
+        ),
+        repo,
+    )
+
+    with TestClient(app) as client:
+        response = client.post("/api/channels/slack/connect")
+
+    assert response.status_code == 400
+    assert "public_base_url" in response.json()["detail"]
+
+    anyio.run(repo.close)
+
+
+def test_connect_discord_uses_request_base_url_without_public_base_url(tmp_path):
+    import anyio
+
+    repo = anyio.run(_make_repo, tmp_path)
+    app = _make_app(
+        ChannelConnectionsConfig.model_validate(
+            {
+                "enabled": True,
+                "mode": "local",
+                "encryption_key": "router-secret",
+                "discord": {
+                    "enabled": True,
+                    "client_id": "discord-client",
+                    "client_secret": "discord-secret",
+                    "bot_token": "discord-bot",
+                    "permissions": "274877975552",
+                },
+            }
+        ),
+        repo,
+    )
+
+    with TestClient(app, base_url="http://localhost:2026") as client:
+        response = client.post("/api/channels/discord/connect")
+
+    assert response.status_code == 200
+    parsed = urlparse(response.json()["url"])
+    query = parse_qs(parsed.query)
+    assert query["redirect_uri"] == ["http://localhost:2026/api/channels/discord/callback"]
+
+    anyio.run(repo.close)
+
+
+def test_connect_discord_without_encryption_key_returns_400(tmp_path):
+    import anyio
+
+    repo = anyio.run(_make_repo, tmp_path, None)
+    app = _make_app(
+        ChannelConnectionsConfig.model_validate(
+            {
+                "enabled": True,
+                "mode": "local",
+                "discord": {
+                    "enabled": True,
+                    "client_id": "discord-client",
+                    "client_secret": "discord-secret",
+                    "bot_token": "discord-bot",
+                },
+            }
+        ),
+        repo,
+    )
+
+    with TestClient(app) as client:
+        response = client.post("/api/channels/discord/connect")
+
+    assert response.status_code == 400
+    assert "encryption_key" in response.json()["detail"]
+
+    anyio.run(repo.close)
+
+
 def test_connect_discord_includes_bot_install_scope_and_permissions(tmp_path):
     import anyio
 
diff --git a/config.example.yaml b/config.example.yaml
index 10ce0d012..b09d02414 100644
--- a/config.example.yaml
+++ b/config.example.yaml
@@ -1143,24 +1143,30 @@ run_events:
 #   socket-mode workers.
 #
 # Security notes:
-# - `enabled: true` requires a public HTTPS base URL for OAuth callbacks and
-#   webhooks.
+# - `mode: local` supports local/private deployments. Telegram deep-link
+#   binding works with long polling and does not require a public URL.
+# - `mode: public` requires `public_base_url`, an externally reachable HTTPS
+#   origin for provider callbacks and webhooks. Slack HTTP Events and Telegram
+#   webhooks need this, or a tunnel, even when DeerFlow itself runs locally.
 # - `encryption_key` is used to encrypt provider tokens at rest. Generate a
-#   long random value and keep it stable. V1 does not support transparent key
-#   rotation; changing it requires users to reconnect.
+#   long random value and keep it stable. Telegram deep-link binding can run
+#   without it because it does not store per-user provider tokens. Slack and
+#   Discord connections require it.
 # - OAuth callbacks and provider webhooks are public routes, but they are
 #   protected by one-time state tokens or provider signatures/secrets.
 #
 # channel_connections:
 #   enabled: false
-#   public_base_url: https://deerflow.example.com
-#   encryption_key: $DEER_FLOW_CHANNEL_CONNECTIONS_KEY
+#   mode: local
+#   # public_base_url: https://deerflow.example.com
+#   # encryption_key: $DEER_FLOW_CHANNEL_CONNECTIONS_KEY
 #
 #   telegram:
 #     enabled: false
 #     bot_token: $TELEGRAM_BOT_TOKEN
 #     bot_username: $TELEGRAM_BOT_USERNAME
-#     webhook_secret: $TELEGRAM_WEBHOOK_SECRET
+#     delivery: polling
+#     # webhook_secret: $TELEGRAM_WEBHOOK_SECRET
 #
 #   slack:
 #     enabled: false
diff --git a/frontend/src/components/workspace/channels/workspace-channels-list.tsx b/frontend/src/components/workspace/channels/workspace-channels-list.tsx
index 9ba3df6c6..edeb865af 100644
--- a/frontend/src/components/workspace/channels/workspace-channels-list.tsx
+++ b/frontend/src/components/workspace/channels/workspace-channels-list.tsx
@@ -1,6 +1,7 @@
 "use client";
 
 import { CheckIcon, LoaderCircleIcon } from "lucide-react";
+import { toast } from "sonner";
 
 import { Button } from "@/components/ui/button";
 import {
@@ -28,12 +29,24 @@ import { ChannelProviderIcon } from "./channel-provider-icon";
 
 function providerCanConnect(provider: ChannelProvider): boolean {
   return (
-    provider.enabled &&
-    provider.configured &&
+    (provider.connectable ?? (provider.enabled && provider.configured)) &&
     provider.connection_status !== "connected"
   );
 }
 
+function getProviderDisabledReason(
+  provider: ChannelProvider,
+  t: ReturnType<typeof useI18n>["t"],
+): string | undefined {
+  if (!provider.enabled) {
+    return t.channels.disabled;
+  }
+  if (!provider.configured) {
+    return t.channels.unconfigured;
+  }
+  return provider.unavailable_reason ?? undefined;
+}
+
 export function WorkspaceChannelsList() {
   const { open: isSidebarOpen } = useSidebar();
   const { t } = useI18n();
@@ -91,9 +104,7 @@ export function WorkspaceChannelsList() {
                     isConnected && "gap-1",
                   )}
                   disabled={!canConnect || isPending}
-                  title={
-                    !provider.configured ? t.channels.unconfigured : undefined
-                  }
+                  title={getProviderDisabledReason(provider, t)}
                   onClick={() => {
                     const connectWindow = prepareConnectWindow();
                     void connectMutation
@@ -101,7 +112,14 @@ export function WorkspaceChannelsList() {
                       .then((result) =>
                         openConnectUrl(result.url, connectWindow),
                       )
-                      .catch(() => closeConnectWindow(connectWindow));
+                      .catch((error) => {
+                        closeConnectWindow(connectWindow);
+                        toast.error(
+                          error instanceof Error
+                            ? error.message
+                            : t.channels.unavailable,
+                        );
+                      });
                   }}
                 >
                   {isPending ? (
diff --git a/frontend/src/components/workspace/settings/channels-settings-page.tsx b/frontend/src/components/workspace/settings/channels-settings-page.tsx
index ec9e4b111..b074765ec 100644
--- a/frontend/src/components/workspace/settings/channels-settings-page.tsx
+++ b/frontend/src/components/workspace/settings/channels-settings-page.tsx
@@ -7,6 +7,7 @@ import {
   PlugIcon,
   UnplugIcon,
 } from "lucide-react";
+import { toast } from "sonner";
 
 import { Badge } from "@/components/ui/badge";
 import { Button } from "@/components/ui/button";
@@ -64,6 +65,9 @@ function getStatusLabel(
   if (!provider.configured) {
     return t.channels.unconfigured;
   }
+  if (provider.unavailable_reason) {
+    return t.channels.unavailableShort;
+  }
   const status = connection?.status ?? provider.connection_status;
   if (status === "connected") {
     return t.channels.connected;
@@ -77,6 +81,19 @@ function getStatusLabel(
   return t.channels.notConnected;
 }
 
+function getProviderDisabledReason(
+  provider: ChannelProvider,
+  t: ReturnType<typeof useI18n>["t"],
+): string | undefined {
+  if (!provider.enabled) {
+    return t.channels.disabled;
+  }
+  if (!provider.configured) {
+    return t.channels.unconfigured;
+  }
+  return provider.unavailable_reason ?? undefined;
+}
+
 function ChannelProviderItem({
   provider,
   connection,
@@ -88,7 +105,9 @@ function ChannelProviderItem({
   const connectMutation = useConnectChannelProvider();
   const disconnectMutation = useDisconnectChannelConnection();
   const isConnected = connection?.status === "connected";
-  const canConnect = provider.enabled && provider.configured && !isConnected;
+  const canConnect =
+    (provider.connectable ?? (provider.enabled && provider.configured)) &&
+    !isConnected;
   const isConnecting =
     connectMutation.isPending &&
     connectMutation.variables === provider.provider;
@@ -97,6 +116,7 @@ function ChannelProviderItem({
     disconnectMutation.variables === connection?.id;
   const connectionLabel = connection ? getConnectionLabel(connection) : null;
   const statusLabel = getStatusLabel(provider, connection, t);
+  const unavailableReason = getProviderDisabledReason(provider, t);
 
   return (
     <Item variant="outline" className="w-full items-start">
@@ -117,6 +137,9 @@ function ChannelProviderItem({
         <ItemDescription className="line-clamp-none">
           {getProviderDescription(provider, t.channels.descriptions)}
           {connectionLabel ? ` ${t.channels.connectedAs(connectionLabel)}` : ""}
+          {!isConnected && provider.unavailable_reason
+            ? ` ${provider.unavailable_reason}`
+            : ""}
         </ItemDescription>
       </ItemContent>
       <ItemActions className="ml-auto">
@@ -140,13 +163,20 @@ function ChannelProviderItem({
             type="button"
             size="sm"
             disabled={!canConnect || isConnecting}
-            title={!provider.configured ? t.channels.unconfigured : undefined}
+            title={unavailableReason}
             onClick={() => {
               const connectWindow = prepareConnectWindow();
               void connectMutation
                 .mutateAsync(provider.provider)
                 .then((result) => openConnectUrl(result.url, connectWindow))
-                .catch(() => closeConnectWindow(connectWindow));
+                .catch((error) => {
+                  closeConnectWindow(connectWindow);
+                  toast.error(
+                    error instanceof Error
+                      ? error.message
+                      : t.channels.unavailable,
+                  );
+                });
             }}
           >
             {isConnecting ? (
diff --git a/frontend/src/core/channels/types.ts b/frontend/src/core/channels/types.ts
index d139c5a74..a82ef998b 100644
--- a/frontend/src/core/channels/types.ts
+++ b/frontend/src/core/channels/types.ts
@@ -5,6 +5,8 @@ export interface ChannelProvider {
   display_name: string;
   enabled: boolean;
   configured: boolean;
+  connectable?: boolean;
+  unavailable_reason?: string | null;
   auth_mode: string;
   connection_status: string;
 }
diff --git a/frontend/src/core/i18n/locales/en-US.ts b/frontend/src/core/i18n/locales/en-US.ts
index 7edc4c22b..2515da145 100644
--- a/frontend/src/core/i18n/locales/en-US.ts
+++ b/frontend/src/core/i18n/locales/en-US.ts
@@ -268,6 +268,7 @@ export const enUS: Translations = {
     disabled: "Disabled",
     unconfigured: "Not configured",
     unavailable: "Channel connections are unavailable right now.",
+    unavailableShort: "Unavailable",
     descriptions: {
       telegram: "Telegram direct messages through your DeerFlow bot.",
       slack: "Slack workspace messages and mentions.",
diff --git a/frontend/src/core/i18n/locales/types.ts b/frontend/src/core/i18n/locales/types.ts
index 85968b990..9a18450c1 100644
--- a/frontend/src/core/i18n/locales/types.ts
+++ b/frontend/src/core/i18n/locales/types.ts
@@ -199,6 +199,7 @@ export interface Translations {
     disabled: string;
     unconfigured: string;
     unavailable: string;
+    unavailableShort: string;
     descriptions: Record<string, string>;
     connectedAs: (name: string) => string;
   };
diff --git a/frontend/src/core/i18n/locales/zh-CN.ts b/frontend/src/core/i18n/locales/zh-CN.ts
index 832522c80..88a95c063 100644
--- a/frontend/src/core/i18n/locales/zh-CN.ts
+++ b/frontend/src/core/i18n/locales/zh-CN.ts
@@ -256,6 +256,7 @@ export const zhCN: Translations = {
     disabled: "已停用",
     unconfigured: "未配置",
     unavailable: "当前无法使用渠道连接。",
+    unavailableShort: "不可用",
     descriptions: {
       telegram: "通过 DeerFlow Bot 接收 Telegram 私聊消息。",
       slack: "接收 Slack 工作区消息和提及。",