feat(hub): embed agent images via Feishu upload + release v0.0.36

Materialize markdown image refs on agent finish: fetch/read bytes, upload
im.v1.image, and render native card img elements so remote image URLs no
longer trip Feishu content-security. Stream masks image URLs mid-run;
card failure falls back to plain text plus standalone image messages.

Docs: clarify im:resource covers outbound Agent image send.

hub/src/feishu/card/builder.ts

@@ -12,6 +12,7 @@
  */
 
 import type { ToolUseTraceStep } from "./trace-store.js";
+import type { CardContentSegment } from "../outboundImages.js";
 
 // ---------------------------------------------------------------------------
 // Types
@@ -58,6 +59,7 @@ function toolIcon(toolName: string): string {
 export function buildAgentCard(params: {
   phase: CardPhase;
   text: string;
+  contentSegments?: readonly CardContentSegment[] | undefined;
   reasoningText: string | undefined;
   toolUseSteps: ToolUseTraceStep[];
   toolUseElapsedMs: number | undefined;
@@ -65,19 +67,19 @@ export function buildAgentCard(params: {
   interrupted: boolean | undefined;
   runId: string | undefined;
 }): Record<string, unknown> {
-  const { phase, text, reasoningText, toolUseSteps, toolUseElapsedMs, isError, interrupted } = params;
+  const { phase, text, contentSegments, reasoningText, toolUseSteps, toolUseElapsedMs, isError, interrupted } = params;
   const elements: unknown[] = [];
 
   // Tool-use panel (always present if there are steps)
   if (toolUseSteps.length > 0) {
     elements.push(buildToolUsePanel(toolUseSteps, toolUseElapsedMs, phase !== "complete"));
-  } else if (phase === "thinking" || (phase === "streaming" && text === "")) {
+  } else if (phase === "thinking" || (phase === "streaming" && text === "" && (contentSegments === undefined || contentSegments.length === 0))) {
     elements.push(buildPendingToolUsePanel());
   }
 
   // Reasoning panel
   if (reasoningText !== undefined && reasoningText !== "") {
-    if (phase === "streaming" && text === "") {
+    if (phase === "streaming" && text === "" && (contentSegments === undefined || contentSegments.length === 0)) {
       // Still thinking: show reasoning inline
       elements.push({
         tag: "markdown",
@@ -90,12 +92,11 @@ export function buildAgentCard(params: {
     }
   }
 
-  // Main text content
-  if (text !== "") {
-    elements.push({
-      tag: "markdown",
-      content: truncateText(text, MAX_TEXT_LENGTH),
-    });
+  // Main answer: either materialized segments (markdown + Feishu-hosted images)
+  // or a single markdown block.
+  const answerElements = buildAnswerElements(text, contentSegments);
+  if (answerElements.length > 0) {
+    elements.push(...answerElements);
   } else if (phase === "thinking" && toolUseSteps.length === 0 && (reasoningText === undefined || reasoningText === "")) {
     elements.push({
       tag: "markdown",
@@ -401,6 +402,43 @@ function escapeMarkdown(value: string): string {
   return value.replace(/\\/g, "\\\\").replace(/([`*_{}[\]<>])/g, "\\$1");
 }
 
+function buildAnswerElements(
+  text: string,
+  contentSegments: readonly CardContentSegment[] | undefined,
+): unknown[] {
+  if (contentSegments !== undefined && contentSegments.length > 0) {
+    const elements: unknown[] = [];
+    let remaining = MAX_TEXT_LENGTH;
+    for (const segment of contentSegments) {
+      if (segment.type === "image") {
+        elements.push({
+          tag: "img",
+          img_key: segment.imgKey,
+          alt: { tag: "plain_text", content: segment.alt },
+          mode: "fit_horizontal",
+          preview: true,
+        });
+        continue;
+      }
+      if (segment.content === "" || remaining <= 0) continue;
+      const slice = segment.content.length <= remaining
+        ? segment.content
+        : truncateText(segment.content, remaining);
+      remaining -= slice.length;
+      elements.push({
+        tag: "markdown",
+        content: slice,
+      });
+    }
+    return elements;
+  }
+  if (text === "") return [];
+  return [{
+    tag: "markdown",
+    content: truncateText(text, MAX_TEXT_LENGTH),
+  }];
+}
+
 function truncateText(value: string, maxLength: number): string {
   return value.length <= maxLength ? value : `${value.slice(0, maxLength - 3)}...`;
 }