feat(platform): add standalone HTTP Bot adapter

A first-class, vendor-neutral message-platform adapter (http_bot) for server-to-server integrations (LangBot Space ticketing et al). Drives a pipeline over plain HTTP with no long-lived connection: - Inbound: signed POST to the existing unified webhook route /bots/<uuid>, carrying a caller-defined session_id mapped to the LangBot launcher id via get_launcher_id -> per-session isolation. Preserves pipeline-native N->1 aggregation for free. - Outbound: each reply_message / reply_message_chunk becomes one signed callback POST to the config-only callback_url, delivered in per-session sequence order with retry/backoff -> 1->M multi-reply. - Sub-paths: /reset (drop a session) and /sync (block for the collapsed reply). - Auth: symmetric HMAC-SHA256 both directions (timestamp + replay window), no JWT/Turnstile, no socket. Decisions: callback URL is config-only (SSRF closed); reset + sync shipped; Python + TS reference clients shipped (signing verified byte-identical 3-way). No core changes: the unified webhook router, aggregator, query pool and pipeline are untouched. Adapter is auto-discovered from platform/sources/. Adds: src/langbot/pkg/platform/sources/http_bot.{py,yaml,svg} src/langbot/pkg/platform/sources/http_bot_signing.py docs/platforms/http-bot.md, docs/http-bot-openapi.json examples/http-bot/{client.py,client.ts,README.md} Updates docs/HTTP_BOT_ADAPTER_DESIGN.md (status: implemented).
2026-06-22 13:34:24 +00:00 · 2026-06-21 21:45:37 -04:00
parent 87f4b9c838
commit c85b9401b8
10 changed files with 1615 additions and 22 deletions
@@ -1,13 +1,29 @@
 # HTTP Bot Adapter — Design Document

-> Status: **Draft / RFC** · Target branch: `feat/http-bot-adapter` · Author: LangBot core
+> Status: **Implemented** · Branch: `feat/http-bot-adapter` · Author: LangBot core
 >
-> A first-class, **standalone** message-platform adapter that lets any external
-> system (e.g. LangBot Space ticketing, an internal back-office, a CRM, a custom
-> web app) talk to a LangBot pipeline over plain HTTP — **inbound** by POSTing
-> messages in, **outbound** by receiving replies on a callback URL — with full
-> support for the pipeline's native N→1 aggregation and 1→M multi-reply
-> semantics, and **without** holding a long-lived WebSocket connection.
+> A first-class, **standalone** message-platform adapter (`http_bot`) that lets
+> any external system (e.g. LangBot Space ticketing, an internal back-office, a
+> CRM, a custom web app) talk to a LangBot pipeline over plain HTTP — **inbound**
+> by POSTing messages in, **outbound** by receiving replies on a callback URL —
+> with full support for the pipeline's native N→1 aggregation and 1→M
+> multi-reply semantics, and **without** holding a long-lived WebSocket
+> connection.
+>
+> **Shipped in this branch:**
+> - `src/langbot/pkg/platform/sources/http_bot.yaml` — adapter manifest (auto-discovered)
+> - `src/langbot/pkg/platform/sources/http_bot.py` — `HttpBotAdapter`
+> - `src/langbot/pkg/platform/sources/http_bot_signing.py` — HMAC helpers
+> - `src/langbot/pkg/platform/sources/http_bot.svg` — icon
+> - `docs/platforms/http-bot.md` — integration guide
+> - `docs/http-bot-openapi.json` — machine-readable contract
+> - `examples/http-bot/` — Python + TypeScript reference clients
+>
+> **Final decisions (resolving the original open questions):**
+> 1. Callback URL is **config-only** — never accepted per-message (SSRF closed).
+> 2. **Session reset is provided** — `POST /bots/<uuid>/reset` keyed by `session_id`.
+> 3. Reference **clients are provided** — `examples/http-bot/client.py` + `client.ts`.
+> 4. **Sync convenience mode is included** — `POST /bots/<uuid>/sync` (opt-in, lossy).

 ---

@@ -244,9 +260,8 @@ Body:
    "id": "user-5567",
    "name": "Alice"
  },
-  "callback_url": "https://space.langbot.app/api/lb/callback",  // optional; overrides config default
  "message": [                         // REQUIRED. A LangBot MessageChain (list of segments).
-    { "type": "Text", "text": "Export keeps failing on the dashboard." },
+    { "type": "Plain", "text": "Export keeps failing on the dashboard." },
    { "type": "Image", "url": "https://.../screenshot.png" }
  ]
 }
@@ -294,7 +309,7 @@ Body:
  "is_final": false,                    // false for intermediate/streamed parts
  "stream": false,                      // true when this is a streamed chunk
  "message": [
-    { "type": "Text", "text": "Looking into it — checking your export logs…" }
+    { "type": "Plain", "text": "Looking into it — checking your export logs…" }
  ],
  "timestamp": "2026-06-22T09:00:01Z"
 }
@@ -495,7 +510,7 @@ alone, push a message and observe a multi-part reply on their callback within
 ```bash
 BOT=https://your-langbot/bots/2f1c....
 SECRET=supersecret
-BODY='{"session_id":"ticket-10293","message":[{"type":"Text","text":"hello"}],"callback_url":"https://your-callback/recv"}'
+BODY='{"session_id":"ticket-10293","message":[{"type":"Plain","text":"hello"}]}'
 TS=$(date +%s)
 SIG="sha256=$(printf '%s.%s' "$TS" "$BODY" | openssl dgst -sha256 -hmac "$SECRET" -r | cut -d' ' -f1)"
 curl -sS -X POST "$BOT" \
@@ -537,15 +552,24 @@ pool, or the pipeline. That is the design's main payoff.

 ---

-## 15. Open questions
+## 15. Resolved decisions

-1. **Callback URL trust** — static (config-only) vs per-message override? Draft
-   allows both; per-message is convenient but widens SSRF surface. Lock to
-   config-only in prod?
-2. **Session lifecycle** — when does a `session_id` "end"? Do we expose a
-   `POST /bots/<uuid>/reset` keyed by `session_id` (mirrors the WS `reset`)?
-3. **Group semantics** — for `session_type: group`, what is the `sender`
-   identity model the Space ticket maps to?
-4. **Backpressure policy** — drop, block, or buffer when a caller's callback is
-   persistently down? (Draft: bounded per-session queue, then drop-oldest +
-   log.)
+1. **Callback URL trust** — **config-only.** The inbound message may not carry a
+   `callback_url`; replies always go to the bot-config URL. Closes the SSRF
+   vector where a leaked inbound secret could redirect replies.
+2. **Session lifecycle** — **`POST /bots/<uuid>/reset`** (body `{session_id,
+   session_type?}`) drops the matching session from the session manager; the
+   next message starts a fresh conversation. Implemented via sub-path routing in
+   `handle_unified_webhook`.
+3. **Group semantics** — for `session_type: group`, `session_id` is the group/
+   launcher id; `sender.id` (and optional `sender.group_name`) identify the
+   member. A Space ticket maps to one `session_id`.
+4. **Backpressure** — bounded per-session outbound queue (maxlen 1000); on
+   overflow the oldest reply is dropped and a warning logged, so a persistently
+   down callback can never exhaust memory.
+
+### Still open / deferred (see §13)
+
+- Durable outbound queue (persist + replay across restarts).
+- Per-caller API keys with rotation/scopes for multi-tenant Space usage.
+- SSE outbound option and a dashboard test console.
@@ -0,0 +1,198 @@
+{
+  "openapi": "3.0.3",
+  "info": {
+    "title": "LangBot HTTP Bot Adapter",
+    "version": "1.0.0",
+    "description": "Server-to-server HTTP integration for a LangBot pipeline. Inbound messages are POSTed to the unified webhook route; replies are delivered to a configured callback URL (one POST per reply part). All requests are HMAC-SHA256 signed. See docs/platforms/http-bot.md."
+  },
+  "paths": {
+    "/bots/{bot_uuid}": {
+      "post": {
+        "summary": "Push a message into the pipeline (fire-and-collect)",
+        "description": "Returns 202 immediately. Replies arrive asynchronously on the configured callback URL. Reuse the same session_id within the aggregation window to merge multiple messages into one turn (N->1).",
+        "parameters": [
+          { "$ref": "#/components/parameters/BotUuid" },
+          { "$ref": "#/components/parameters/Timestamp" },
+          { "$ref": "#/components/parameters/Signature" },
+          { "$ref": "#/components/parameters/Idempotency" }
+        ],
+        "requestBody": {
+          "required": true,
+          "content": { "application/json": { "schema": { "$ref": "#/components/schemas/InboundMessage" } } }
+        },
+        "responses": {
+          "202": {
+            "description": "Accepted (queued for the pipeline)",
+            "content": { "application/json": { "schema": { "$ref": "#/components/schemas/AcceptedResponse" } } }
+          },
+          "400": { "$ref": "#/components/responses/Error" },
+          "401": { "$ref": "#/components/responses/Error" },
+          "409": { "$ref": "#/components/responses/Error" },
+          "413": { "$ref": "#/components/responses/Error" }
+        }
+      }
+    },
+    "/bots/{bot_uuid}/sync": {
+      "post": {
+        "summary": "Push a message and wait for the collapsed reply",
+        "description": "Blocking convenience mode. Waits for is_final and returns all reply parts collapsed into one array. Lossy (no sequence/streaming). One in-flight sync per session_id.",
+        "parameters": [
+          { "$ref": "#/components/parameters/BotUuid" },
+          { "$ref": "#/components/parameters/Timestamp" },
+          { "$ref": "#/components/parameters/Signature" }
+        ],
+        "requestBody": {
+          "required": true,
+          "content": { "application/json": { "schema": { "$ref": "#/components/schemas/InboundMessage" } } }
+        },
+        "responses": {
+          "200": {
+            "description": "The collapsed reply",
+            "content": { "application/json": { "schema": { "$ref": "#/components/schemas/SyncResponse" } } }
+          },
+          "400": { "$ref": "#/components/responses/Error" },
+          "401": { "$ref": "#/components/responses/Error" }
+        }
+      }
+    },
+    "/bots/{bot_uuid}/reset": {
+      "post": {
+        "summary": "Reset a session's conversation",
+        "parameters": [
+          { "$ref": "#/components/parameters/BotUuid" },
+          { "$ref": "#/components/parameters/Timestamp" },
+          { "$ref": "#/components/parameters/Signature" }
+        ],
+        "requestBody": {
+          "required": true,
+          "content": {
+            "application/json": {
+              "schema": {
+                "type": "object",
+                "required": ["session_id"],
+                "properties": {
+                  "session_id": { "type": "string" },
+                  "session_type": { "type": "string", "enum": ["person", "group"] }
+                }
+              }
+            }
+          }
+        },
+        "responses": {
+          "200": { "description": "Reset done" },
+          "400": { "$ref": "#/components/responses/Error" },
+          "401": { "$ref": "#/components/responses/Error" }
+        }
+      }
+    }
+  },
+  "components": {
+    "parameters": {
+      "BotUuid": {
+        "name": "bot_uuid", "in": "path", "required": true,
+        "schema": { "type": "string", "format": "uuid" }
+      },
+      "Timestamp": {
+        "name": "X-LB-Timestamp", "in": "header", "required": true,
+        "description": "Unix seconds; rejected if more than +/-300s from server time.",
+        "schema": { "type": "string" }
+      },
+      "Signature": {
+        "name": "X-LB-Signature", "in": "header", "required": true,
+        "description": "sha256=<hex> of HMAC-SHA256(secret, \"{timestamp}.\" + raw_body).",
+        "schema": { "type": "string" }
+      },
+      "Idempotency": {
+        "name": "X-LB-Idempotency-Key", "in": "header", "required": false,
+        "description": "Dedup key; a repeat within the dedup window returns 409.",
+        "schema": { "type": "string" }
+      }
+    },
+    "schemas": {
+      "Segment": {
+        "type": "object",
+        "required": ["type"],
+        "properties": {
+          "type": { "type": "string", "enum": ["Plain", "Image", "Voice", "File", "At", "Quote"] },
+          "text": { "type": "string", "description": "For type=Plain." },
+          "url": { "type": "string", "description": "For media types." },
+          "base64": { "type": "string", "description": "For media types (data URI or raw base64)." }
+        }
+      },
+      "InboundMessage": {
+        "type": "object",
+        "required": ["session_id", "message"],
+        "properties": {
+          "session_id": { "type": "string", "description": "Caller-defined; maps 1:1 to a LangBot session." },
+          "session_type": { "type": "string", "enum": ["person", "group"], "default": "person" },
+          "sender": {
+            "type": "object",
+            "properties": {
+              "id": { "type": "string" },
+              "name": { "type": "string" },
+              "group_name": { "type": "string", "description": "For session_type=group." }
+            }
+          },
+          "message": { "type": "array", "items": { "$ref": "#/components/schemas/Segment" } }
+        }
+      },
+      "AcceptedResponse": {
+        "type": "object",
+        "properties": {
+          "code": { "type": "integer", "example": 0 },
+          "msg": { "type": "string", "example": "accepted" },
+          "data": {
+            "type": "object",
+            "properties": {
+              "session_id": { "type": "string" },
+              "accepted_message_id": { "type": "string", "example": "in_01H..." },
+              "aggregating": { "type": "boolean" }
+            }
+          }
+        }
+      },
+      "SyncResponse": {
+        "type": "object",
+        "properties": {
+          "code": { "type": "integer", "example": 0 },
+          "msg": { "type": "string", "example": "ok" },
+          "data": {
+            "type": "object",
+            "properties": {
+              "session_id": { "type": "string" },
+              "reply_to": { "type": "string" },
+              "message": { "type": "array", "items": { "$ref": "#/components/schemas/Segment" } }
+            }
+          }
+        }
+      },
+      "Callback": {
+        "type": "object",
+        "description": "Delivered by LangBot to your callback_url, one POST per reply part. Signed with the outbound secret.",
+        "properties": {
+          "session_id": { "type": "string" },
+          "reply_to": { "type": "string", "description": "The accepted_message_id this answers." },
+          "sequence": { "type": "integer", "description": "1-based ordinal within the turn." },
+          "is_final": { "type": "boolean", "description": "True on the last part of the turn." },
+          "stream": { "type": "boolean" },
+          "message": { "type": "array", "items": { "$ref": "#/components/schemas/Segment" } },
+          "timestamp": { "type": "string", "format": "date-time" }
+        }
+      },
+      "ErrorEnvelope": {
+        "type": "object",
+        "properties": {
+          "code": { "type": "integer", "example": 40101 },
+          "msg": { "type": "string", "example": "invalid signature: signature_mismatch" },
+          "data": { "nullable": true }
+        }
+      }
+    },
+    "responses": {
+      "Error": {
+        "description": "Error envelope",
+        "content": { "application/json": { "schema": { "$ref": "#/components/schemas/ErrorEnvelope" } } }
+      }
+    }
+  }
+}
@@ -0,0 +1,256 @@
+# HTTP Bot Adapter — Integration Guide
+
+Integrate **any backend system** with a LangBot pipeline over plain HTTP. Push
+messages in via a signed webhook; receive replies on a callback URL. No
+long-lived connection, full support for message **aggregation** (many inbound
+messages merged into one turn) and **multi-part replies** (one turn → many
+outbound messages).
+
+This is the right adapter for **server-to-server** integrations — ticketing
+systems, CRMs, internal tools, custom web backends. (For an in-browser,
+real-time chat widget, use the embeddable Web Page Bot instead.)
+
+> **5-minute goal:** stand up a callback receiver, send a message, and watch a
+> multi-part reply arrive — using the reference client in
+> [`examples/http-bot/`](../../examples/http-bot/).
+
+---
+
+## 1. Mental model
+
+```
+Your backend  ──(1) POST signed message──►  LangBot   /bots/<bot_uuid>
+                                            (pipeline runs: aggregate → think → reply)
+Your callback ◄─(2) POST signed reply(s)──  LangBot   one POST per reply part
+```
+
+- **(1) Inbound** is *fire-and-collect*: LangBot answers `202 Accepted`
+  immediately and does **not** return the pipeline result on that response.
+- **(2) Outbound** replies arrive later as separate signed POSTs to your
+  `callback_url`. A single turn may produce **several** callbacks (e.g. a tool
+  call narration followed by the final answer).
+- Everything is keyed by a **`session_id` you choose** (e.g. a ticket number).
+  Each `session_id` maps to one isolated LangBot conversation.
+
+---
+
+## 2. Create the bot
+
+1. In the LangBot dashboard, add a bot and choose the **HTTP Bot** platform.
+2. Fill in the config:
+
+   | Field | Required | Notes |
+   |---|---|---|
+   | **Inbound Signing Secret** | yes | Your backend signs inbound requests with this. |
+   | **Outbound Callback URL** | yes | Where LangBot POSTs replies. **Config-only** — cannot be overridden per message (SSRF protection). |
+   | **Outbound Signing Secret** | no | LangBot signs callbacks with this; defaults to the inbound secret. |
+   | **Default Session Type** | no | `person` (default) or `group`. |
+   | **Require Inbound Signature** | no | Keep `true` in production. |
+   | **Callback Timeout / Max Retries** | no | Defaults: 15s, 3 retries. |
+
+3. Bind the bot to a **pipeline** and **enable** it.
+4. Copy the **Inbound Webhook URL** shown in the config — it looks like
+   `https://your-langbot/bots/<bot_uuid>`.
+
+---
+
+## 3. The signature scheme
+
+Both directions use the same dependency-free HMAC-SHA256 scheme:
+
+```
+signing_string = "{timestamp}." + raw_body_bytes
+signature      = "sha256=" + hex(HMAC_SHA256(secret, signing_string))
+```
+
+Sent as headers:
+
+| Header | Meaning |
+|---|---|
+| `X-LB-Timestamp` | Unix seconds. Rejected if more than **±300s** from server time. |
+| `X-LB-Signature` | `sha256=<hex>` over `"{timestamp}." + body`. |
+| `X-LB-Idempotency-Key` | *(optional, inbound)* dedup key; retries with the same key return `409`. |
+
+Verify outbound callbacks the same way, using the **outbound** secret (or the
+inbound secret if you left it blank).
+
+A six-line reference implementation is in `examples/http-bot/client.py`
+(`sign()` / `verify()`); a Node/TS version is in `client.ts`.
+
+---
+
+## 4. Send your first message (curl)
+
+```bash
+BOT="https://your-langbot/bots/<bot_uuid>"
+SECRET="your-inbound-secret"
+BODY='{"session_id":"ticket-10293","message":[{"type":"Plain","text":"Export keeps failing on the dashboard."}]}'
+TS=$(date +%s)
+SIG="sha256=$(printf '%s.%s' "$TS" "$BODY" | openssl dgst -sha256 -hmac "$SECRET" -r | cut -d' ' -f1)"
+
+curl -sS -X POST "$BOT" \
+  -H "Content-Type: application/json" \
+  -H "X-LB-Timestamp: $TS" \
+  -H "X-LB-Signature: $SIG" \
+  -d "$BODY"
+# -> 202 {"code":0,"msg":"accepted","data":{"session_id":"ticket-10293","accepted_message_id":"in_...","aggregating":true}}
+```
+
+The reply(s) will be POSTed to your configured callback URL shortly after.
+
+---
+
+## 5. Inbound request format
+
+`POST /bots/{bot_uuid}`
+
+```jsonc
+{
+  "session_id": "ticket-10293",     // REQUIRED. Your stable id. Maps 1:1 to a LangBot session.
+  "session_type": "person",         // optional: "person" | "group"; default from config
+  "sender": {                       // optional metadata, surfaced to the pipeline/plugins
+    "id": "user-5567",
+    "name": "Alice"
+  },
+  "message": [                      // REQUIRED. A LangBot MessageChain (array of segments).
+    { "type": "Plain", "text": "Export keeps failing on the dashboard." },
+    { "type": "Image", "url": "https://example.com/screenshot.png" }
+  ]
+}
+```
+
+**Message segments.** Text uses `{"type":"Plain","text":"..."}`. Images use
+`{"type":"Image","url":"..."}` (or `base64`). Other supported types: `Voice`,
+`File`, `At`, `Quote`.
+
+> Note: the callback URL is **not** accepted in the body — it is taken only from
+> bot config. This is deliberate (prevents an attacker who obtains the inbound
+> secret from redirecting replies to an arbitrary host).
+
+### Aggregation (N → 1)
+
+If your pipeline has **message aggregation** enabled, send several messages with
+the **same `session_id`** within the aggregation window and they are merged into
+**one** pipeline turn. No special flag — just reuse the `session_id`.
+
+---
+
+## 6. Outbound callback format
+
+LangBot POSTs each reply part to your `callback_url`:
+
+```jsonc
+{
+  "session_id": "ticket-10293",     // echoes the inbound session
+  "reply_to": "in_01H...",          // the accepted_message_id this answers
+  "sequence": 1,                    // 1-based ordinal within this turn
+  "is_final": false,                // true on the last part of the turn
+  "stream": false,                  // true for streamed chunks
+  "message": [ { "type": "Plain", "text": "Looking into it…" } ],
+  "timestamp": "2026-06-22T09:00:01Z"
+}
+```
+
+Your endpoint should return `2xx` quickly. Non-2xx / timeout → LangBot retries
+with exponential backoff (up to `callback_max_retries`).
+
+### Multi-part replies (1 → M)
+
+One turn may emit multiple callbacks, delivered **in `sequence` order** for a
+given session:
+
+```
+seq=1 is_final=false  "Checking your export logs…"
+seq=2 is_final=false  "Found 2 failed exports."
+seq=3 is_final=true   "Fixed — please try again."
+```
+
+Stitch by `session_id` + `sequence`; the turn is complete when
+`is_final: true` arrives.
+
+---
+
+## 7. Reset a session
+
+Start a fresh conversation for a `session_id` (drops history):
+
+```
+POST /bots/{bot_uuid}/reset
+{ "session_id": "ticket-10293", "session_type": "person" }
+→ 200 { "code":0, "msg":"reset", "data": { "session_id":"ticket-10293", "removed": true } }
+```
+
+Signed exactly like an inbound message.
+
+---
+
+## 8. Synchronous convenience mode
+
+If you don't need streaming/multi-part and just want one reply back on the same
+HTTP call, POST to `/sync`. LangBot waits for the turn to finish and returns all
+parts **collapsed** into one array:
+
+```
+POST /bots/{bot_uuid}/sync
+{ "session_id": "ticket-10293", "message": [ { "type":"Plain", "text":"hi" } ] }
+→ 200 { "code":0, "msg":"ok",
+        "data": { "session_id":"ticket-10293", "reply_to":"in_...",
+                  "message": [ {"type":"Plain","text":"..."}, ... ] } }
+```
+
+This is **lossy** (you lose `sequence` / streaming boundaries) and blocks up to
+`callback_timeout × 4` seconds. Prefer the callback model for anything
+real-time or multi-part. Only one in-flight `/sync` per `session_id`.
+
+---
+
+## 9. Error envelope
+
+```jsonc
+{ "code": 40101, "msg": "invalid signature: signature_mismatch", "data": null }
+```
+
+| HTTP | code | meaning |
+|---|---|---|
+| 202 | 0 | accepted |
+| 400 | 40001 | malformed body / missing `session_id` or `message` |
+| 401 | 40101 | bad/expired signature |
+| 409 | 40901 | duplicate idempotency key |
+| 413 | 41301 | message too large (>1 MiB) |
+| 500 | 50001 | internal error |
+
+---
+
+## 10. Try it end-to-end in 5 minutes
+
+```bash
+cd examples/http-bot
+pip install flask requests
+
+# Terminal 1 — your callback receiver (point the bot's callback_url here, e.g. via a tunnel):
+python client.py serve --port 8900 --secret SHARED_SECRET
+
+# Terminal 2 — push a message:
+python client.py push \
+  --url https://your-langbot/bots/<bot_uuid> \
+  --secret SHARED_SECRET \
+  --session ticket-1 \
+  --text "hello"
+```
+
+Watch Terminal 1 print each reply part (`[part ]` / `[FINAL]`) with its
+sequence number — that's 1→M working, signatures verified.
+
+A machine-readable contract is in
+[`docs/http-bot-openapi.json`](../http-bot-openapi.json).
+
+---
+
+## 11. Security checklist
+
+- Keep **Require Inbound Signature** on in production.
+- Use **HTTPS** callback URLs; the URL is config-only (no per-message override).
+- Treat the secrets like passwords; rotate via the dashboard.
+- The inbound route is unauthenticated at the framework level **by design** —
+  security comes entirely from the HMAC signature, so never disable it on a
+  public deployment.