fix: enforce final tag gating (#754) (thanks @mcinteerj)

CHANGELOG.md

@@ -93,6 +93,7 @@
 - CLI/Update: preserve base environment when passing overrides to update subprocesses. (#713) — thanks @danielz1z.
 - Agents: treat message tool errors as failures so fallback replies still send; require `to` + `message` for `action=send`. (#717) — thanks @theglove44.
 - Agents: preserve reasoning items on tool-only turns.
+- Agents: enforce `<final>` gating for reasoning-tag providers to prevent tag/reasoning leaks. (#754) — thanks @mcinteerj.
 - Agents/Subagents: wait for completion before announcing, align wait timeout with run timeout, and make announce prompts more emphatic.
 - Agents: route subagent transcripts to the target agent sessions directory and add regression coverage. (#708) — thanks @xMikeMickelson.
 - Agents/Tools: preserve action enums when flattening tool schemas. (#708) — thanks @xMikeMickelson.

src/agents/pi-embedded-subscribe.test.ts

@@ -16,7 +16,7 @@ describe("subscribeEmbeddedPiSession", () => {
     { tag: "thought", open: "<thought>", close: "</thought>" },
     { tag: "antthinking", open: "<antthinking>", close: "</antthinking>" },
   ] as const;
-  it("filters to <final> and falls back when tags are malformed", () => {
+  it("filters to <final> and suppresses output without a start tag", () => {
     let handler: ((evt: unknown) => void) | undefined;
     const session: StubSession = {
       subscribe: (fn) => {
@@ -38,6 +38,7 @@ describe("subscribeEmbeddedPiSession", () => {
       onAgentEvent,
     });
 
+    handler?.({ type: "message_start", message: { role: "assistant" } });
     handler?.({
       type: "message_update",
       message: { role: "assistant" },
@@ -53,11 +54,7 @@ describe("subscribeEmbeddedPiSession", () => {
 
     onPartialReply.mockReset();
 
-    handler?.({
-      type: "message_end",
-      message: { role: "assistant" },
-    });
-
+    handler?.({ type: "message_start", message: { role: "assistant" } });
     handler?.({
       type: "message_update",
       message: { role: "assistant" },
@@ -67,8 +64,7 @@ describe("subscribeEmbeddedPiSession", () => {
       },
     });
 
-    const secondPayload = onPartialReply.mock.calls[0][0];
-    expect(secondPayload.text).toContain("Oops no start");
+    expect(onPartialReply).not.toHaveBeenCalled();
   });
 
   it("does not require <final> when enforcement is off", () => {

src/agents/pi-embedded-subscribe.ts

@@ -36,9 +36,6 @@ import {
   promoteThinkingTagsToBlocks,
 } from "./pi-embedded-utils.js";
 
-const THINKING_TAG_RE = /<\s*\/?\s*(?:think(?:ing)?|thought|antthinking)\s*>/gi;
-const THINKING_OPEN_RE = /<\s*(?:think(?:ing)?|thought|antthinking)\s*>/i;
-const THINKING_CLOSE_RE = /<\s*\/\s*(?:think(?:ing)?|thought|antthinking)\s*>/i;
 const THINKING_TAG_SCAN_RE =
   /<\s*(\/?)\s*(?:think(?:ing)?|thought|antthinking)\s*>/gi;
 const FINAL_TAG_SCAN_RE = /<\s*(\/?)\s*final\s*>/gi;
@@ -182,11 +179,6 @@ export function subscribeEmbeddedPiSession(params: {
   }) => void;
   enforceFinalTag?: boolean;
 }) {
-  if (params.enforceFinalTag) {
-    log.debug("subscribeEmbeddedPiSession: enforceFinalTag is ENABLED");
-  } else {
-    log.debug("subscribeEmbeddedPiSession: enforceFinalTag is DISABLED");
-  }
   const assistantTexts: string[] = [];
   const toolMetas: Array<{ toolName?: string; meta?: string }> = [];
   const toolMetaById = new Map<string, string | undefined>();
@@ -202,7 +194,6 @@ export function subscribeEmbeddedPiSession(params: {
   let blockBuffer = "";
   // Track if a streamed chunk opened a <think> block (stateful across chunks).
   const blockState = { thinking: false, final: false };
-  const streamState = { thinking: false, final: false };
   let lastStreamedAssistant: string | undefined;
   let lastStreamedReasoning: string | undefined;
   let lastBlockReplyText: string | undefined;
@@ -220,8 +211,6 @@ export function subscribeEmbeddedPiSession(params: {
     blockChunker?.reset();
     blockState.thinking = false;
     blockState.final = false;
-    streamState.thinking = false;
-    streamState.final = false;
     lastStreamedAssistant = undefined;
     lastBlockReplyText = undefined;
     lastStreamedReasoning = undefined;
@@ -373,6 +362,7 @@ export function subscribeEmbeddedPiSession(params: {
     // hallucinations (e.g. Minimax copying the style) from leaking, but we
     // do not enforce buffering/extraction logic.
     if (!params.enforceFinalTag) {
+      FINAL_TAG_SCAN_RE.lastIndex = 0;
       return processed.replace(FINAL_TAG_SCAN_RE, "");
     }
 
@@ -405,19 +395,6 @@ export function subscribeEmbeddedPiSession(params: {
     }
     state.final = inFinal;
 
-    // Log the result of the stripping for debugging purposes
-    if (params.enforceFinalTag && (everInFinal || processed.length > 0)) {
-        log.debug(JSON.stringify({
-            raw: processed.slice(0, 100),
-            stripped: result.slice(0, 100),
-            inFinal,
-            everInFinal,
-            rawLen: processed.length,
-            strippedLen: result.length,
-            tag: "DEBUG_STRIP"
-        }));
-    }
-
     // Strict Mode: If enforcing final tags, we MUST NOT return content unless
     // we have seen a <final> tag. Otherwise, we leak "thinking out loud" text
     // (e.g. "**Locating Manulife**...") that the model emitted without <think> tags.
@@ -936,8 +913,6 @@ export function subscribeEmbeddedPiSession(params: {
           blockChunker?.reset();
           blockState.thinking = false;
           blockState.final = false;
-          streamState.thinking = false;
-          streamState.final = false;
           lastStreamedAssistant = undefined;
         }
       }
@@ -1021,8 +996,6 @@ export function subscribeEmbeddedPiSession(params: {
         }
         blockState.thinking = false;
         blockState.final = false;
-        streamState.thinking = false;
-        streamState.final = false;
         if (pendingCompactionRetry > 0) {
           resolveCompactionRetry();
         } else {

src/auto-reply/reply.ts

@@ -1156,9 +1156,6 @@ export async function getReplyFromConfig(
     resolvedQueue.mode === "collect" ||
     resolvedQueue.mode === "steer-backlog";
   const authProfileId = sessionEntry?.authProfileOverride;
-  // DEBUG: Check provider for reasoning tag
-  const shouldEnforce = isReasoningTagProvider(provider);
-  // defaultRuntime.log(`[DEBUG] reply.ts: provider='${provider}', isReasoningTagProvider=${shouldEnforce}`);
 
   const followupRun = {
     prompt: queuedBody,
@@ -1198,15 +1195,7 @@ export async function getReplyFromConfig(
       ownerNumbers:
         command.ownerList.length > 0 ? command.ownerList : undefined,
       extraSystemPrompt: extraSystemPrompt || undefined,
-      ...(isReasoningTagProvider(provider)
-        ? (() => {
-            logVerbose(`[reply] Enforcing final tag for provider: ${provider}`);
-            return { enforceFinalTag: true };
-          })()
-        : (() => {
-            logVerbose(`[reply] NOT enforcing final tag for provider: ${provider}`);
-            return {};
-          })()),
+      ...(isReasoningTagProvider(provider) ? { enforceFinalTag: true } : {}),
     },
   };
 

src/utils/provider-utils.ts

@@ -7,10 +7,12 @@
  * (e.g. <think> and <final>) in the text stream, rather than using native
  * API fields for reasoning/thinking.
  */
-export function isReasoningTagProvider(provider: string | undefined | null): boolean {
+export function isReasoningTagProvider(
+  provider: string | undefined | null,
+): boolean {
   if (!provider) return false;
   const normalized = provider.trim().toLowerCase();
-  
+
   // Check for exact matches or known prefixes/substrings for reasoning providers
   if (
     normalized === "ollama" ||
@@ -19,7 +21,7 @@ export function isReasoningTagProvider(provider: string | undefined | null): boo
   ) {
     return true;
   }
-  
+
   // Handle google-antigravity and its model variations (e.g. google-antigravity/gemini-3)
   if (normalized.includes("google-antigravity")) {
     return true;
@@ -29,6 +31,6 @@ export function isReasoningTagProvider(provider: string | undefined | null): boo
   if (normalized.includes("minimax")) {
     return true;
   }
-  
+
   return false;
 }