Merge pull request 'fix(bridge): recover inline-prefixed metadata in user message body' (#4) from fix/inline-metadata-strip into main

OpenClaw's canonical convention is to emit metadata envelopes (chat_id,
sender, reply target, …) as SEPARATE user-role messages folded into the
openai-completions request right after the real one — `extractLatestUserMessage`
skips those whole.

Fabric.OpenclawPlugin's dispatch does not split: it passes metadata
blocks and the real user content as ONE merged user-message body,
separated by blank lines. With the prior filter that meant the entire
turn was dropped with "no user message found" (HTTP 400) because the
first line matched a sentinel — the actual prompt sitting after the
metadata blocks never reached the bridge.

When the whole-body check fails for a single-message body, walk past
leading sentinel-prefixed blocks (sentinel header + optional ```json
code fence + blank-line separator) and use whatever non-metadata block
follows. Falls back to the previous "skip entirely" semantics when the
body is metadata-only.

End-user symptom that surfaced this: every contractor agent (Claude /
Gemini) subscribed to a Fabric channel silently failed to reply to
sub-discussion messages during recruitment — fabric dispatch said
"completed" in 1.6s but trajectory had `assistantTexts: []`,
`terminalError: non_deliverable_terminal_turn`,
`errorMessage: "400 \"no user message found\""`. Surfaced
recruiting developer1 on prod-t2 2026-05-31.

plugin/web/input-filter.ts

@@ -61,6 +61,51 @@ function isRuntimeContextMessage(text: string): boolean {
   return INBOUND_META_SENTINELS.includes(firstLine);
 }
 
+/**
+ * Strip *prefixed* metadata blocks from a single user message body.
+ *
+ * Background: OpenClaw's older / canonical convention is to emit metadata
+ * envelopes (chat_id, sender, reply target, …) as SEPARATE user-role
+ * messages folded into the openai-completions request right after the real
+ * one. `extractLatestUserMessage` skips those separate messages whole.
+ *
+ * The Fabric channel plugin (Fabric.OpenclawPlugin) does not split: it
+ * passes the metadata blocks and the actual user content as ONE merged
+ * user-message body, separated by blank lines. Result: a Fabric inbound
+ * turn has a single user message whose first line matches a sentinel, so
+ * `isRuntimeContextMessage` returned true and the whole turn was dropped
+ * with "no user message found" (HTTP 400). Symptom: every contractor agent
+ * subscribed to a Fabric channel silently fails to reply.
+ *
+ * Strip leading sentinel-prefixed blocks (sentinel header + optional code
+ * fence + blank-line separator) until we hit a block whose first line is
+ * NOT a sentinel — that's the real prompt. Returns "" if the entire body
+ * is metadata-only (still a no-op turn, same as before).
+ */
+function stripPrefixedMetadataBlocks(raw: string): string {
+  // Split on blank-line block boundaries. Within a metadata block the JSON
+  // code fence has only single newlines, so it stays in the same chunk as
+  // its sentinel header.
+  const blocks = raw.split(/\n\n+/);
+  const kept: string[] = [];
+  let stillStripping = true;
+  for (const block of blocks) {
+    if (stillStripping) {
+      const trimmed = block.trimStart();
+      const firstLine = trimmed.split("\n", 1)[0].trim();
+      if (
+        INBOUND_META_SENTINELS.includes(firstLine) ||
+        trimmed.startsWith(LEGACY_RUNTIME_CONTEXT_MARKER)
+      ) {
+        continue; // drop this prefix block
+      }
+      stillStripping = false;
+    }
+    kept.push(block);
+  }
+  return kept.join("\n\n").trim();
+}
+
 /**
  * Extract the latest user-authored message from the OpenClaw request.
  *
@@ -85,7 +130,18 @@ export function extractLatestUserMessage(req: BridgeInboundRequest): string {
   for (let i = userMessages.length - 1; i >= 0; i -= 1) {
     const raw = messageText(userMessages[i]);
     if (!raw) continue;
-    if (isRuntimeContextMessage(raw)) continue;
+    // First try the separate-message convention (Discord/Telegram path): a
+    // user message whose entire body is one metadata envelope — skip whole.
+    if (isRuntimeContextMessage(raw)) {
+      // ...but also try inline-prefixed-metadata recovery (Fabric path):
+      // some channels splice metadata + real content into one body. Walk
+      // past leading sentinel blocks; if any non-metadata block follows,
+      // that's the prompt. If nothing follows, this turn really is pure
+      // metadata and we keep skipping.
+      const stripped = stripPrefixedMetadataBlocks(raw);
+      if (stripped) return stripOpenClawTimestampPrefix(stripped);
+      continue;
+    }
     return stripOpenClawTimestampPrefix(raw);
   }
   return "";

plugin/web/server.ts

@@ -596,14 +596,47 @@ export function createBridgeServer(config: BridgeServerConfig): http.Server {
           return;
         }
 
-        const execFn = (toolInstance as { execute: (id: string, args: unknown) => Promise<{ content?: Array<{ type: string; text?: string }> }> }).execute;
-        const toolResult = await execFn(randomUUID(), toolArgs);
+        const execFn = (toolInstance as { execute: (id: string, args: unknown) => Promise<unknown> }).execute;
+        const toolResultRaw = await execFn(randomUUID(), toolArgs);
 
-        // Extract text content from AgentToolResult
-        const text = (toolResult.content ?? [])
-          .filter((c) => c.type === "text" && c.text)
-          .map((c) => c.text as string)
-          .join("\n");
+        // Normalize the result shape. OpenClaw plugins return one of:
+        //   (a) AgentToolResult — { content: [{type:'text', text:'...'}, ...] }
+        //       used by tools that wrap via asContent() (e.g. all
+        //       Dialectic.OpenclawPlugin tools).
+        //   (b) raw JSON-able object — { ok:true, ...domain fields }
+        //       used by tools that return data directly (e.g. every
+        //       Fabric.OpenclawPlugin tool: fabric-channel-list,
+        //       fabric-guild-list, fabric-send-message, etc).
+        //   (c) null / undefined — fire-and-forget (rare).
+        //
+        // Pre-2026-05-24 the bridge ONLY handled shape (a); shape (b)
+        // silently returned "(no result)" to Claude Code (bug:
+        // fabric-channel-list and friends were unusable from contractor
+        // agents even though the tool actually ran successfully).
+        let text = "";
+        if (toolResultRaw == null) {
+          text = "";
+        } else if (
+          typeof toolResultRaw === "object" &&
+          Array.isArray((toolResultRaw as { content?: unknown }).content)
+        ) {
+          // Shape (a)
+          const content = (toolResultRaw as { content: Array<{ type: string; text?: string }> }).content;
+          text = content
+            .filter((c) => c.type === "text" && c.text)
+            .map((c) => c.text as string)
+            .join("\n");
+        } else if (typeof toolResultRaw === "string") {
+          text = toolResultRaw;
+        } else {
+          // Shape (b) — serialize the whole object as JSON. Claude Code
+          // is happy to parse JSON tool results.
+          try {
+            text = JSON.stringify(toolResultRaw);
+          } catch {
+            text = String(toolResultRaw);
+          }
+        }
 
         sendJson(res, 200, { result: text || "(no result)" });
       } catch (err) {