fix: preserve slack hook alert content

docs/automation/hooks.md

@@ -114,7 +114,7 @@ Each event includes: `type`, `action`, `sessionKey`, `timestamp`, `messages` (pu
 
 **Command events** (`command:new`, `command:reset`): `context.sessionEntry`, `context.previousSessionEntry`, `context.commandSource`, `context.workspaceDir`, `context.cfg`.
 
-**Message events** (`message:received`): `context.from`, `context.content`, `context.channelId`, `context.metadata` (provider-specific data including `senderId`, `senderName`, `guildId`).
+**Message events** (`message:received`): `context.from`, `context.content`, `context.channelId`, `context.metadata` (provider-specific data including `senderId`, `senderName`, `guildId`). `context.content` prefers a nonblank command body for command-like messages, then falls back to the raw inbound body and generic body; it does not include agent-only enrichment such as thread history or link summaries.
 
 **Message events** (`message:sent`): `context.to`, `context.content`, `context.success`, `context.channelId`.
 

extensions/slack/src/monitor/message-handler/prepare.test.ts

@@ -536,7 +536,7 @@ describe("slack prepareSlackMessage inbound contract", () => {
       subtype: "bot_message",
       attachments: [
         {
-          text: "Readiness probe failed: Get http://10.42.13.132:8000/status: context deadline exceeded",
+          text: "Readiness probe failed: Get https://status.example.test/readiness: context deadline exceeded",
         },
       ],
     });
@@ -545,6 +545,11 @@ describe("slack prepareSlackMessage inbound contract", () => {
 
     expect(prepared).toBeTruthy();
     expect(prepared!.ctxPayload.RawBody).toContain("Readiness probe failed");
+    // Slack message attachments can carry the user-visible body even when the
+    // top-level message text is empty.
+    expect(prepared!.ctxPayload.CommandBody).toBe("");
+    expect(prepared!.ctxPayload.BodyForCommands).toBe("");
+    expect(prepared!.ctxPayload.BodyForAgent).toContain("Readiness probe failed");
   });
 
   it("drops bot-authored room messages when allowBots is true but no owner is present (#59284)", async () => {

src/hooks/message-hook-mappers.test.ts

@@ -97,6 +97,30 @@ describe("message hook mappers", () => {
     expect(canonical.guildId).toBe("guild-1");
   });
 
+  it("falls back to raw body when command body is blank", () => {
+    const canonical = deriveInboundMessageHookContext(
+      makeInboundCtx({
+        BodyForCommands: " \n\t",
+        RawBody: "Readiness probe failed",
+      }),
+    );
+
+    expect(canonical.content).toBe("Readiness probe failed");
+    expect(toPluginMessageReceivedEvent(canonical).content).toBe("Readiness probe failed");
+    expect(toInternalMessageReceivedContext(canonical).content).toBe("Readiness probe failed");
+  });
+
+  it("keeps nonblank command body ahead of raw body for hook content", () => {
+    const canonical = deriveInboundMessageHookContext(
+      makeInboundCtx({
+        BodyForCommands: "/status",
+        RawBody: "Readiness probe failed",
+      }),
+    );
+
+    expect(canonical.content).toBe("/status");
+  });
+
   it("supports explicit content/messageId overrides", () => {
     const canonical = deriveInboundMessageHookContext(makeInboundCtx(), {
       content: "override-content",

src/hooks/message-hook-mappers.ts

@@ -80,6 +80,10 @@ export type CanonicalSentMessageHookContext = {
   groupId?: string;
 };
 
+function readNonBlankString(value: unknown): string | undefined {
+  return typeof value === "string" && value.trim().length > 0 ? value : undefined;
+}
+
 export function deriveInboundMessageHookContext(
   ctx: FinalizedMsgContext,
   overrides?: {
@@ -89,13 +93,10 @@ export function deriveInboundMessageHookContext(
 ): CanonicalInboundMessageHookContext {
   const content =
     overrides?.content ??
-    (typeof ctx.BodyForCommands === "string"
-      ? ctx.BodyForCommands
-      : typeof ctx.RawBody === "string"
-        ? ctx.RawBody
-        : typeof ctx.Body === "string"
-          ? ctx.Body
-          : "");
+    readNonBlankString(ctx.BodyForCommands) ??
+    readNonBlankString(ctx.RawBody) ??
+    readNonBlankString(ctx.Body) ??
+    "";
   const channelId = normalizeLowercaseStringOrEmpty(
     ctx.OriginatingChannel ?? ctx.Surface ?? ctx.Provider ?? "",
   );