feat(gateway): add LINE Messaging API platform plugin (#23197)

* feat(gateway): add LINE Messaging API platform plugin

Adds LINE as a bundled platform plugin under `plugins/platforms/line/`,
synthesized from the strongest pieces of seven open community PRs. The
adapter requires zero core edits — `Platform("line")` is auto-discovered
via the bundled-plugin scan in `gateway/config.py`, and all hooks
(setup, env-enablement, cron delivery, standalone send) are wired
through `register_platform()` kwargs the way IRC and Teams do it.

Highlights merged into one plugin:

- **Reply token preferred, Push fallback.** Try the free reply token
  first (single-use, ~60s TTL); fall back to metered Push when the
  token is absent, expired, or rejected. (PR #21023)
- **Slow-LLM Template Buttons postback.** When the LLM is still running
  past `LINE_SLOW_RESPONSE_THRESHOLD` (default 45s), the adapter burns
  the original reply token to send a "Get answer" button bubble. The
  user taps it to fetch the cached answer via a fresh reply token —
  also free. State machine: PENDING → READY → DELIVERED, ERROR for
  cancelled runs (orphan resolves to `LINE_INTERRUPTED_TEXT` after
  /stop). Set threshold to 0 to disable. (PR #18153)
- **Three-allowlist gating** — separate user / group / room allowlists
  with `LINE_ALLOW_ALL_USERS=true` dev-only escape hatch. (PR #18153)
- **Markdown URL preservation.** Strip bold/italic/code-fence/heading
  markers (LINE renders them literally) but keep `[label](url)` →
  `label (url)` so URLs stay tappable. (PR #18153)
- **System-message bypass** for `⚡ Interrupting`, `⏳ Queued`, etc. —
  busy-acks reach the user as visible bubbles instead of being
  swallowed into the postback cache. (PR #18153)
- **Media via public HTTPS URLs.** LINE doesn't accept binary uploads;
  images/audio/video must be HTTPS-reachable. The adapter serves
  registered tempfiles under `/line/media/<token>/<filename>` from the
  same aiohttp app. Allowed-roots traversal guard covers
  `tempfile.gettempdir()`, `/tmp` (→ `/private/tmp` on macOS), and
  `HERMES_HOME`. `LINE_PUBLIC_URL` overrides URL construction for
  setups behind tunnels/proxies. (PR #8398)
- **5-message-per-call batching.** LINE rejects >5 messages per
  Reply/Push; smart-chunker caps text at 4500 chars per bubble.
- **Inbound dedup** via `webhookEventId` LRU. (PR #21023)
- **Self-message filter** via `/v2/bot/info` userId lookup. (PR #21023)
- **Loading-animation indicator** wired to LINE's `chat/loading/start`
  endpoint, DM-only (LINE rejects it for groups/rooms). (PR #21023)
- **Out-of-process cron delivery** via `_standalone_send`, so
  `deliver: line` cron jobs work even when cron runs detached from
  the gateway.
- **Webhook hardening** — 1 MiB body cap, constant-time HMAC-SHA256
  signature verification, dedup, scoped lock so two profiles can't
  bind the same channel.

Validation
----------

- `scripts/run_tests.sh tests/gateway/test_line_plugin.py` →
  73 passed in 1.05s
- `scripts/run_tests.sh tests/gateway/test_line_plugin.py
  tests/gateway/test_irc_adapter.py
  tests/gateway/test_plugin_platform_interface.py
  tests/gateway/test_platform_registry.py
  tests/gateway/test_config.py` → 193 passed, 7 skipped
- E2E import + register + signature roundtrip + `Platform("line")`
  bundled-plugin discovery verified against current `origin/main`.

Closes the seven open LINE PRs (#18153, #16832, #6676, #21023, #14942,
#14988, #8398) by superseding them with a single plugin-form
implementation that takes the best idea from each.

Co-authored-by: pwlee <32443648+leepoweii@users.noreply.github.com>
Co-authored-by: Jetha Chan <jetha@google.com>
Co-authored-by: Cattia <openclaw@liyangchen.me>
Co-authored-by: perng <charles@perng.com>
Co-authored-by: Soichiro Yoshimura <soichiro0111.dev@gmail.com>
Co-authored-by: David Zhou <77736378+David-0x221Eight@users.noreply.github.com>
Co-authored-by: Yu-ga <74749461+yuga-hashimoto@users.noreply.github.com>

* docs(platforms): document platform-specific slow-LLM UX pattern

Add a 'Platform-Specific Slow-LLM UX' section to the platform-adapter
developer guide covering the _keep_typing override pattern that LINE
uses for its Template Buttons postback flow.

Three subsections:
- Pattern: subclass _keep_typing to layer mid-flight UX (with code)
- Pattern: subclass send to route through a cache instead of sending
- When this pattern is appropriate (vs. always-Push fallback)

Plus a short pointer in gateway/platforms/ADDING_A_PLATFORM.md so
tree-readers find the prose walkthrough on the docsite.

Filed because the LINE plugin (PR #23197) was the first bundled
adapter to need this pattern — every prior plugin (irc, teams,
google_chat) handles slow responses with the default typing-loop and
a regular send_text. Documenting now while the rationale is fresh.

---------

Co-authored-by: pwlee <32443648+leepoweii@users.noreply.github.com>
Co-authored-by: Jetha Chan <jetha@google.com>
Co-authored-by: Cattia <openclaw@liyangchen.me>
Co-authored-by: perng <charles@perng.com>
Co-authored-by: Soichiro Yoshimura <soichiro0111.dev@gmail.com>
Co-authored-by: David Zhou <77736378+David-0x221Eight@users.noreply.github.com>
Co-authored-by: Yu-ga <74749461+yuga-hashimoto@users.noreply.github.com>

plugins/platforms/line/__init__.py

@@ -0,0 +1,3 @@
+from .adapter import register
+
+__all__ = ["register"]

plugins/platforms/line/plugin.yaml

@@ -0,0 +1,65 @@
+name: line-platform
+label: LINE
+kind: platform
+version: 1.0.0
+description: >
+  LINE Messaging API gateway adapter for Hermes Agent.
+  Runs an aiohttp webhook server that receives LINE webhook events
+  (with HMAC-SHA256 signature verification) and relays messages between
+  LINE chats (1:1, groups, rooms) and the Hermes agent. Outbound replies
+  prefer the free reply token and fall back to the metered Push API
+  when the token has expired or is absent. Slow LLM responses surface a
+  Template Buttons postback bubble so the user can fetch the answer with
+  a fresh reply token (free) once it's ready.
+author: Hermes Agent contributors
+# ``requires_env`` and ``optional_env`` entries are surfaced in the
+# ``hermes config`` UI via the platform-plugin env var injector in
+# ``hermes_cli/config.py``.
+requires_env:
+  - name: LINE_CHANNEL_ACCESS_TOKEN
+    description: "LINE channel long-lived access token (LINE Developers Console > Messaging API > Channel access token)"
+    prompt: "LINE channel access token"
+    url: "https://developers.line.biz/console/"
+    password: true
+  - name: LINE_CHANNEL_SECRET
+    description: "LINE channel secret (used for HMAC-SHA256 webhook signature verification)"
+    prompt: "LINE channel secret"
+    url: "https://developers.line.biz/console/"
+    password: true
+optional_env:
+  - name: LINE_PORT
+    description: "Webhook listen port (default: 8646)"
+    prompt: "Webhook port"
+    password: false
+  - name: LINE_HOST
+    description: "Webhook bind host (default: 0.0.0.0)"
+    prompt: "Webhook host"
+    password: false
+  - name: LINE_PUBLIC_URL
+    description: "Public HTTPS base URL for serving images/audio/video to LINE (e.g. https://my-tunnel.example.com). Required for media sending when the bind address is not directly reachable."
+    prompt: "Public HTTPS base URL"
+    password: false
+  - name: LINE_ALLOWED_USERS
+    description: "Comma-separated LINE user IDs allowed to DM the bot (U-prefixed)"
+    prompt: "Allowed user IDs (comma-separated)"
+    password: false
+  - name: LINE_ALLOWED_GROUPS
+    description: "Comma-separated LINE group IDs the bot will respond in (C-prefixed)"
+    prompt: "Allowed group IDs (comma-separated)"
+    password: false
+  - name: LINE_ALLOWED_ROOMS
+    description: "Comma-separated LINE room IDs the bot will respond in (R-prefixed)"
+    prompt: "Allowed room IDs (comma-separated)"
+    password: false
+  - name: LINE_ALLOW_ALL_USERS
+    description: "Allow any LINE user to talk to the bot (dev only — disables allowlist)"
+    prompt: "Allow all users? (true/false)"
+    password: false
+  - name: LINE_HOME_CHANNEL
+    description: "Default user/group/room ID for cron / notification delivery"
+    prompt: "Home channel ID (or empty)"
+    password: false
+  - name: LINE_SLOW_RESPONSE_THRESHOLD
+    description: "Seconds before the slow-LLM postback button fires (default: 45; set 0 to disable and always Push-fallback)"
+    prompt: "Slow response threshold (seconds)"
+    password: false