fix(mattermost): surface reactions support

CHANGELOG.md

@@ -11,6 +11,7 @@ Docs: https://docs.openclaw.ai
 - iOS/Talk: add a `Voice Directive Hint` toggle for Talk Mode prompts so users can disable ElevenLabs voice-switching instructions to save tokens when not needed. (#18250) Thanks @zeulewan.
 - Telegram/Agents: add inline button `style` support (`primary|success|danger`) across message tool schema, Telegram action parsing, send pipeline, and runtime prompt guidance. (#18241) Thanks @obviyus.
 - Telegram: surface user message reactions as system events, with configurable `channels.telegram.reactionNotifications` scope. (#10075) Thanks @Glucksberg.
+- Mattermost: add emoji reaction actions plus reaction event notifications, including an explicit boolean `remove` flag to avoid accidental removals. (#18608) Thanks @echo931.
 - Discord: expose native `/exec` command options (host/security/ask/node) so Discord slash commands get autocomplete and structured inputs. Thanks @thewilloftheshadow.
 - Discord: allow reusable interactive components with `components.reusable=true` so buttons, selects, and forms can be used multiple times before expiring. Thanks @thewilloftheshadow.
 - Cron/Gateway: separate per-job webhook delivery (`delivery.mode = "webhook"`) from announce delivery, enforce valid HTTP(S) webhook URLs, and keep a temporary legacy `notify + cron.webhook` fallback for stored jobs. (#17901) Thanks @advaitpaliwal.
@@ -30,7 +31,6 @@ Docs: https://docs.openclaw.ai
 - UI/Usage: replace lingering undefined `var(--text-muted)` usage with `var(--muted)` in usage date-range and chart styles to keep muted text visible across themes. (#17975) Thanks @jogelin.
 - UI/Usage: preserve selected-range totals when timeline data is downsampled by bucket-aggregating timeseries points (instead of dropping intermediate points), so filtered tokens/cost stay accurate. (#17959) Thanks @jogelin.
 - UI/Sessions: refresh the sessions table only after successful deletes and preserve delete errors on cancel/failure paths, so deleted sessions disappear automatically without masking delete failures. (#18507)
-- Mattermost: harden reaction handling by requiring an explicit boolean `remove` flag and routing reaction websocket events to the reaction handler, preventing string `"true"` values from being treated as removes and avoiding double-processing of reaction events as posts. (#18608) Thanks @echo931.
 - Scripts/UI/Windows: fix `pnpm ui:*` spawn `EINVAL` failures by restoring shell-backed launch for `.cmd`/`.bat` runners, narrowing shell usage to launcher types that require it, and rejecting unsafe forwarded shell metacharacters in UI script args. (#18594)
 - Hooks/Session-memory: recover `/new` conversation summaries when session pointers are reset-path or missing `sessionFile`, and consistently prefer the newest `.jsonl.reset.*` transcript candidate for fallback extraction. (#18088)
 - Auto-reply/Sessions: prevent stale thread ID leakage into non-thread sessions so replies stay in the main DM after topic interactions. (#18528) Thanks @j2h4u.

docs/channels/mattermost.md

@@ -114,6 +114,26 @@ Use these target formats with `openclaw message send` or cron/webhooks:
 
 Bare IDs are treated as channels.
 
+## Reactions (message tool)
+
+- Use `message action=react` with `channel=mattermost`.
+- `messageId` is the Mattermost post id.
+- `emoji` accepts names like `thumbsup` or `:+1:` (colons are optional).
+- Set `remove=true` (boolean) to remove a reaction.
+- Reaction add/remove events are forwarded as system events to the routed agent session.
+
+Examples:
+
+```
+message action=react channel=mattermost target=channel:<channelId> messageId=<postId> emoji=thumbsup
+message action=react channel=mattermost target=channel:<channelId> messageId=<postId> emoji=thumbsup remove=true
+```
+
+Config:
+
+- `channels.mattermost.actions.reactions`: enable/disable reaction actions (default true).
+- Per-account override: `channels.mattermost.accounts.<id>.actions.reactions`.
+
 ## Multi-account
 
 Mattermost supports multiple accounts under `channels.mattermost.accounts`:

extensions/mattermost/src/channel.test.ts

@@ -37,6 +37,12 @@ describe("mattermostPlugin", () => {
     });
   });
 
+  describe("capabilities", () => {
+    it("declares reactions support", () => {
+      expect(mattermostPlugin.capabilities?.reactions).toBe(true);
+    });
+  });
+
   describe("messageActions", () => {
     it("exposes react when mattermost is configured", () => {
       const cfg: OpenClawConfig = {

extensions/mattermost/src/channel.ts

@@ -167,6 +167,7 @@ export const mattermostPlugin: ChannelPlugin<ResolvedMattermostAccount> = {
   },
   capabilities: {
     chatTypes: ["direct", "channel", "group", "thread"],
+    reactions: true,
     threads: true,
     media: true,
   },