diff --git a/src/agents/tools/slack-actions.test.ts b/src/agents/tools/slack-actions.test.ts
index 1e86fe85b..4113328a6 100644
--- a/src/agents/tools/slack-actions.test.ts
+++ b/src/agents/tools/slack-actions.test.ts
@@ -131,10 +131,7 @@ describe("handleSlackAction", () => {
   it("requires canvases to be enabled", async () => {
     const cfg = { channels: { slack: { botToken: "tok" } } } as ClawdbotConfig;
     await expect(
-      handleSlackAction(
-        { action: "createCanvas", title: "Test", content: "hello" },
-        cfg,
-      ),
+      handleSlackAction({ action: "createCanvas", title: "Test", content: "hello" }, cfg),
     ).rejects.toThrow(/Slack canvases are disabled/);
   });
 
@@ -142,10 +139,7 @@ describe("handleSlackAction", () => {
     const cfg = {
       channels: { slack: { botToken: "tok", actions: { canvases: true } } },
     } as ClawdbotConfig;
-    await handleSlackAction(
-      { action: "createCanvas", title: "Test", content: "hello" },
-      cfg,
-    );
+    await handleSlackAction({ action: "createCanvas", title: "Test", content: "hello" }, cfg);
     expect(createSlackCanvas).toHaveBeenCalledWith(
       { title: "Test", content: "hello", channelId: undefined },
       undefined,
@@ -156,10 +150,7 @@ describe("handleSlackAction", () => {
     const cfg = {
       channels: { slack: { botToken: "tok", actions: { canvases: true } } },
     } as ClawdbotConfig;
-    await handleSlackAction(
-      { action: "updateCanvas", canvasId: "C123", content: "update" },
-      cfg,
-    );
+    await handleSlackAction({ action: "updateCanvas", canvasId: "C123", content: "update" }, cfg);
     expect(updateSlackCanvas).toHaveBeenCalledWith(
       { canvasId: "C123", channelId: undefined, content: "update", updateMode: undefined },
       undefined,
diff --git a/src/channels/plugins/message-action-names.ts b/src/channels/plugins/message-action-names.ts
index c884f6da3..1c1e42fa0 100644
--- a/src/channels/plugins/message-action-names.ts
+++ b/src/channels/plugins/message-action-names.ts
@@ -47,6 +47,8 @@ export const CHANNEL_MESSAGE_ACTION_NAMES = [
   "timeout",
   "kick",
   "ban",
+  "canvas-create",
+  "canvas-update",
 ] as const;
 
 export type ChannelMessageActionName = (typeof CHANNEL_MESSAGE_ACTION_NAMES)[number];
diff --git a/src/slack/canvases.test.ts b/src/slack/canvases.test.ts
index 3150a6124..50e657f07 100644
--- a/src/slack/canvases.test.ts
+++ b/src/slack/canvases.test.ts
@@ -56,11 +56,12 @@ describe("extractCanvasRefsFromEvent", () => {
 
 describe("fetchSlackCanvasContent", () => {
   it("downloads and parses JSON canvas content", async () => {
-    const fetchMock = vi.fn(async () =>
-      new Response(JSON.stringify({ text: "hello canvas" }), {
-        status: 200,
-        headers: { "content-type": "application/json" },
-      }),
+    const fetchMock = vi.fn(
+      async () =>
+        new Response(JSON.stringify({ text: "hello canvas" }), {
+          status: 200,
+          headers: { "content-type": "application/json" },
+        }),
     );
     vi.stubGlobal("fetch", fetchMock);
 
@@ -127,11 +128,12 @@ describe("fetchSlackCanvasContent", () => {
   });
 
   it("truncates large payloads", async () => {
-    const fetchMock = vi.fn(async () =>
-      new Response(JSON.stringify({ text: "1234567890" }), {
-        status: 200,
-        headers: { "content-type": "application/json" },
-      }),
+    const fetchMock = vi.fn(
+      async () =>
+        new Response(JSON.stringify({ text: "1234567890" }), {
+          status: 200,
+          headers: { "content-type": "application/json" },
+        }),
     );
     vi.stubGlobal("fetch", fetchMock);
 
diff --git a/src/slack/canvases.ts b/src/slack/canvases.ts
index 76be2e79e..1e81f0013 100644
--- a/src/slack/canvases.ts
+++ b/src/slack/canvases.ts
@@ -173,7 +173,10 @@ function collectJsonText(
   }
 }
 
-function extractTextFromJson(payload: unknown, maxChars: number): { text: string; truncated: boolean } {
+function extractTextFromJson(
+  payload: unknown,
+  maxChars: number,
+): { text: string; truncated: boolean } {
   const results: string[] = [];
   const seen = new Set<string>();
   collectJsonText(payload, { maxChars, results, seen, depth: 0 });
@@ -197,10 +200,22 @@ export async function fetchSlackCanvasContent(params: {
     return { ok: false, error: "no_file_id" };
   }
 
-  let fileInfo: { file?: SlackFile & { title?: string; name?: string; url_private?: string; url_private_download?: string } };
+  let fileInfo: {
+    file?: SlackFile & {
+      title?: string;
+      name?: string;
+      url_private?: string;
+      url_private_download?: string;
+    };
+  };
   try {
     fileInfo = (await client.files.info({ file: fileId })) as {
-      file?: SlackFile & { title?: string; name?: string; url_private?: string; url_private_download?: string };
+      file?: SlackFile & {
+        title?: string;
+        name?: string;
+        url_private?: string;
+        url_private_download?: string;
+      };
     };
   } catch (err) {
     const label = buildErrorLabel(err);
@@ -242,7 +257,11 @@ export async function fetchSlackCanvasContent(params: {
   let extracted: { text: string; truncated: boolean };
   let rawFormat: SlackCanvasContent["rawFormat"] = "unknown";
 
-  if (contentType.includes("application/json") || text.trim().startsWith("{") || text.trim().startsWith("[")) {
+  if (
+    contentType.includes("application/json") ||
+    text.trim().startsWith("{") ||
+    text.trim().startsWith("[")
+  ) {
     rawFormat = "json";
     try {
       const payload = JSON.parse(text);
diff --git a/src/slack/monitor/message-handler/prepare.inbound-contract.test.ts b/src/slack/monitor/message-handler/prepare.inbound-contract.test.ts
index ad643a50b..c0a875275 100644
--- a/src/slack/monitor/message-handler/prepare.inbound-contract.test.ts
+++ b/src/slack/monitor/message-handler/prepare.inbound-contract.test.ts
@@ -151,11 +151,12 @@ describe("slack prepareSlackMessage inbound contract", () => {
   });
 
   it("appends canvas content to the inbound body", async () => {
-    const fetchMock = vi.fn(async () =>
-      new Response(JSON.stringify({ title: "Canvas", text: "hello canvas" }), {
-        status: 200,
-        headers: { "content-type": "application/json" },
-      }),
+    const fetchMock = vi.fn(
+      async () =>
+        new Response(JSON.stringify({ title: "Canvas", text: "hello canvas" }), {
+          status: 200,
+          headers: { "content-type": "application/json" },
+        }),
     );
     vi.stubGlobal("fetch", fetchMock);
 
diff --git a/src/slack/monitor/message-handler/prepare.ts b/src/slack/monitor/message-handler/prepare.ts
index 2027dbd39..51ccd6992 100644
--- a/src/slack/monitor/message-handler/prepare.ts
+++ b/src/slack/monitor/message-handler/prepare.ts
@@ -371,7 +371,8 @@ export async function prepareSlackMessage(params: {
   }
   const canvasContext = canvasBlocks.length > 0 ? canvasBlocks.join("\n\n") : "";
 
-  const baseBody = (message.text ?? "").trim() || media?.placeholder || (canvasContext ? "[Slack canvas]" : "");
+  const baseBody =
+    (message.text ?? "").trim() || media?.placeholder || (canvasContext ? "[Slack canvas]" : "");
   if (!baseBody) return null;
   const rawBody = baseBody;
   const rawBodyWithCanvas = canvasContext ? `${rawBody}\n\n${canvasContext}` : rawBody;