LINE Setup

Run Hermes Agent as a LINE bot via the official LINE Messaging API. The adapter lives as a bundled platform plugin under plugins/platforms/line/ — no core edits, just enable it like any other platform.

LINE is the dominant messaging app in Japan, Taiwan, and Thailand. If your users live there, this is how they reach you.

How the bot responds

Context	Behavior
1:1 chat (U IDs)	Responds to every message
Group chat (C IDs)	Responds when the group is on the allowlist
Multi-user room (R IDs)	Responds when the room is on the allowlist

Inbound text, images, audio, video, files, stickers, and locations are all handled. Outbound text uses the free reply token first (single-use, ~60s window) and falls back to the metered Push API when the token has expired.

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Step 1: Create a LINE Messaging API channel

1. Go to the LINE Developers Console.
2. Create a Provider, then under it a Messaging API channel.
3. From the channel's Basic settings tab, copy the Channel secret.
4. From the Messaging API tab, scroll to Channel access token (long-lived) and click Issue. Copy the token.
5. In the Messaging API tab, also disable Auto-reply messages and Greeting messages so they don't fight your bot's replies.

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Step 2: Expose the webhook port

LINE delivers webhooks over public HTTPS. The default port is 8646 — override with LINE_PORT if needed.

# Cloudflare Tunnel (recommended for production — fixed hostname)
cloudflared tunnel --url http://localhost:8646

# ngrok (good for dev)
ngrok http 8646

# devtunnel
devtunnel create hermes-line --allow-anonymous
devtunnel port create hermes-line -p 8646 --protocol https
devtunnel host hermes-line

Copy the https://... URL — you'll set it as the webhook URL below. Leave the tunnel running while testing. For production, set up a fixed Cloudflare named tunnel so the webhook URL doesn't change on restart.

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Step 3: Configure Hermes

Add to ~/.hermes/.env:

LINE_CHANNEL_ACCESS_TOKEN=YOUR_LONG_LIVED_TOKEN
LINE_CHANNEL_SECRET=YOUR_CHANNEL_SECRET

# Allowlist — at least one of these (or LINE_ALLOW_ALL_USERS=true for dev)
LINE_ALLOWED_USERS=U1234567890abcdef...           # comma-separated U-prefixed IDs
LINE_ALLOWED_GROUPS=C1234567890abcdef...          # optional group IDs
LINE_ALLOWED_ROOMS=R1234567890abcdef...           # optional room IDs

# Required for image / audio / video sends — the public HTTPS base URL
# the tunnel resolves to.  Without it, send_image/voice/video will refuse.
LINE_PUBLIC_URL=https://my-tunnel.example.com

Then in ~/.hermes/config.yaml:

gateway:
  platforms:
    line:
      enabled: true

That's enough — the bundled-plugin scan in gateway/config.py automatically picks up plugins/platforms/line/. No Platform.LINE enum edit, no _create_adapter registration.

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Step 4: Set the webhook URL

Back in the LINE console:

1. Open your channel → Messaging API tab.
2. Under Webhook settings → Webhook URL, paste https://<your-tunnel>/line/webhook (note the /line/webhook path — the adapter listens there).
3. Click Verify. LINE pings the URL; you should see a 200.
4. Toggle Use webhook to On.

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Step 5: Run the gateway

hermes gateway

The agent log shows:

LINE: webhook listening on 0.0.0.0:8646/line/webhook (public: https://my-tunnel.example.com)

Add the bot as a friend from the LINE app (scan the QR in the channel's Messaging API tab) and send it a message.

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Slow LLM responses

LINE's reply token is single-use and expires roughly 60 seconds after the inbound event. Slow LLMs can't reply in time, which would normally force a paid Push API call.

When the LLM is still running past LINE_SLOW_RESPONSE_THRESHOLD seconds (default 45), the adapter consumes the original reply token to send a Template Buttons bubble:

🤔 Still thinking. Tap below to fetch the answer when it's ready.

[ Get answer ]

The user taps Get answer when convenient — that postback delivers a fresh reply token, which the adapter uses to send the cached answer (still free).

State machine: PENDING → READY → DELIVERED, plus ERROR for cancelled runs (the orphan PENDING resolves to "Run was interrupted before completion." after /stop so the persistent button doesn't loop).

To disable the postback button and always Push-fallback instead:

LINE_SLOW_RESPONSE_THRESHOLD=0

For the postback flow to fire reliably, suppress chatter that would consume the reply token before the threshold:

# ~/.hermes/config.yaml
display:
  interim_assistant_messages: false
  platforms:
    line:
      tool_progress: off

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Cron / notification delivery

LINE_HOME_CHANNEL=Uxxxxxxxxxxxxxxxxxxxx     # default delivery target

Cron jobs with deliver: line route to LINE_HOME_CHANNEL. The adapter ships a standalone Push-only sender so cron jobs work even when cron runs in a separate process from the gateway.

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Environment variable reference

Variable	Required	Default	Description
LINE_CHANNEL_ACCESS_TOKEN	yes	—	Long-lived channel access token
LINE_CHANNEL_SECRET	yes	—	Channel secret (HMAC-SHA256 webhook verification)
LINE_HOST	no	0.0.0.0	Webhook bind host
LINE_PORT	no	8646	Webhook bind port
LINE_PUBLIC_URL	for media	—	Public HTTPS base URL; required for image/voice/video sends
LINE_ALLOWED_USERS	one of	—	Comma-separated user IDs (U-prefixed)
LINE_ALLOWED_GROUPS	one of	—	Comma-separated group IDs (C-prefixed)
LINE_ALLOWED_ROOMS	one of	—	Comma-separated room IDs (R-prefixed)
LINE_ALLOW_ALL_USERS	dev only	false	Skip allowlist entirely
LINE_HOME_CHANNEL	no	—	Default cron / notification delivery target
LINE_SLOW_RESPONSE_THRESHOLD	no	45	Seconds before the postback button fires (0 = disabled)
LINE_PENDING_TEXT	no	"🤔 Still thinking…"	Bubble text shown alongside the postback button
LINE_BUTTON_LABEL	no	"Get answer"	Button label
LINE_DELIVERED_TEXT	no	"Already replied ✅"	Reply when an already-delivered button is tapped again
LINE_INTERRUPTED_TEXT	no	"Run was interrupted before completion."	Reply when a /stop orphan button is tapped

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Troubleshooting

"invalid signature" on webhook verify. The Channel secret was copied wrong, or your tunnel rewrote the request body. Verify with curl -i https://<tunnel>/line/webhook/health first — that should return {"status":"ok","platform":"line"}.

Bot receives nothing in groups. Check LINE_ALLOWED_GROUPS includes the C... group ID. To find a group ID, send a test message and grep ~/.hermes/logs/gateway.log for LINE: rejecting unauthorized source — the rejected source dict has the IDs.

send_image fails with "LINE_PUBLIC_URL must be set". LINE's Messaging API does not accept binary uploads — images, audio, and video must be reachable HTTPS URLs. Set LINE_PUBLIC_URL to the tunnel's public hostname and the adapter will serve files from /line/media/<token>/<filename> automatically.

Postback button never appears. Either the LLM responded faster than LINE_SLOW_RESPONSE_THRESHOLD, or another bubble (tool-progress, streaming) consumed the reply token first. See the suppression block under "Slow LLM responses".

"already in use by another profile". The same channel access token is bound to another running Hermes profile. Stop the other gateway or use a separate channel.

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Limitations

• Single bubble per chunk. Each LINE text bubble is capped at 5000 characters, and at most 5 bubbles are sent per Reply/Push call. Longer responses are truncated with an ellipsis.
• No native message editing. LINE has no edit-message API — streaming responses always send fresh bubbles, never edit prior ones.
• No Markdown rendering. Bold (**), italics (*), code fences, and headings render as literal characters. The adapter strips them before sending; URLs are preserved ([label](url) becomes label (url)).
• Loading indicator is DM-only. LINE rejects the chat/loading API for groups and rooms, so the typing indicator only shows in 1:1 chats.