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Add (build) indicator next to model name for build mode comments #115

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Add (build) indicator next to model name for build mode comments #115

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8 changes: 8 additions & 0 deletions app/[owner]/[repo]/[postNumber]/comment-thread.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,11 @@ function CommentItem({

const { postNumber } = useParams<{ postNumber: string }>()

// Check if this is a build mode comment (only relevant for LLM comments)
const isBuildMode =
author.isLlm &&
(comment.content as AgentUIMessage[]).some((m) => m.metadata?.mode === "build")
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@vercel vercel bot Jan 19, 2026

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Build mode indicator fails to display for subsequent messages in multi-turn conversations because mode metadata is only added to the first message of the first step

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📝 Patch Details 
diff --git a/agent/response-agent.ts b/agent/response-agent.ts
index 2f8d0d1..a61fc52 100644
--- a/agent/response-agent.ts
+++ b/agent/response-agent.ts
@@ -366,7 +366,7 @@ async function streamTextStep({
               ...m,
               id: nanoid(),
               metadata:
-                isFirstStep && index === 0 && mode === "build" ? { mode } : {},
+                mode === "build" ? { mode } : {},
             } satisfies AgentUIMessage
           })
         )

Analysis

Bug Explanation

In agent/response-agent.ts around line 367, the code conditionally adds mode metadata only when three conditions are met simultaneously:

  • isFirstStep && index === 0 && mode === "build"

The problem manifests in two scenarios:

Scenario 1: Multiple messages in first step
When the AI generates multiple messages (e.g., text + tool use), only the first message (index === 0) gets the mode metadata. Subsequent messages in the same first step won't have it.

Scenario 2: Multi-turn conversations
When stepCount > 0 (happens in the while loop in responseAgent lines 71-86), isFirstStep = newMessages.length === 0 becomes false. This means NO messages in steps 2 and beyond receive the mode metadata, even though they were generated in build mode.

In comment-thread.tsx line 84, the code checks:

const isBuildMode =
  author.isLlm &&
  (comment.content as AgentUIMessage[]).some((m) => m.metadata?.mode === "build")

This check uses .some(), which needs at least ONE message with the mode metadata. The current logic in response-agent makes this unreliable because:

  • First step, second+ messages: Won't have mode metadata
  • Any messages in steps 2+: Won't have mode metadata

Result: The build mode indicator "(build)" fails to display for real-world multi-turn conversations or when the first response generates multiple messages.

The Fix

Changed line 367 in agent/response-agent.ts from:

metadata: isFirstStep && index === 0 && mode === "build" ? { mode } : {}

To:

metadata: mode === "build" ? { mode } : {}

This ensures that EVERY message generated when mode="build" receives the mode metadata, regardless of step number or message index. Now the .some() check in comment-thread.tsx will reliably find the build mode indication, guaranteeing the indicator displays correctly in all cases.

The fix is minimal, non-breaking, and doesn't require database migrations because it only changes how existing metadata is populated.


const actionLabel = isRootComment ? "posted" : "commented"

const header = (
Expand All @@ -95,6 +100,9 @@ function CommentItem({
<UserAvatar src={author.image} username={author.username} />

{author.name}
{isBuildMode && (
<span className="font-normal text-muted-foreground">(build)</span>
)}
</Link>
<span className="hidden sm:inline">&nbsp;</span>
<span className="mr-1.5 text-muted-foreground text-sm">
Expand Down