[Bug]: Using Explanatory Output Style plugin in CC causes broken output #10711

Activity

1. skyfallwastaken

   added

   bugSomething is broken or behaving incorrectly.Something is broken or behaving incorrectly.

   needs-triageIssue needs maintainer review and initial categorization.Issue needs maintainer review and initial categorization.

   on Sep 8, 2026
2. juliusmarminge commented on Sep 8, 2026

   

   juliusmarminge

   on Sep 8, 2026

   Member

   More actions

   Triage

   Confirmed as a web/desktop markdown rendering bug (minor / cosmetic). The Explanatory Output Style plugin is doing what it is supposed to: a SessionStart hook tells Claude to emit ASCII-art insight fences like:

   ★ Insight ─────────────────────────────────────
   [2–3 educational points]
   ─────────────────────────────────────────────────
   

   Claude Code’s own CLI special-cases that into a boxed callout. T3 does not. We persist the text as a normal assistant message and run it through ChatMarkdown.

   We already tried to meet this halfway in #4344 (closed #3652) by turning on lineBreaks when the message matches ★ Insight. That restored newlines so the block no longer collapses to one paragraph, but the ─ box-drawing still wraps (overflow-wrap: anywhere) and draws a rule through the first insight line — matching the second screenshot. This is leftover from that fix, not a duplicate of #3652.

   Not the same class of issue as #7644 (terminal), #3747 (error JSON), or #1147 (tool metadata leak).

   Where to fix

   • Web/desktop: MessagesTimeline.logic.ts / AssistantTimelineRow / ChatMarkdown
   • Mobile also missing: ThreadFeed AssistantMarkdownContent has no insight detection and does not preserve soft breaks for these blocks

   Suggested fix

   Parse the ★ Insight / trailing ─ fences out of assistant text and render a dedicated callout (title + body). Do not send the box-drawing through markdown. Same split on web and mobile. The learning-output-style plugin uses the same fence, so one parser covers both.

   Workaround for now: disable the plugin.
3. juliusmarminge

   added

   via-triageFiled through npx t3 triageFiled through npx t3 triage

   acceptedfeature request acceptedfeature request accepted

   and removed

   needs-triageIssue needs maintainer review and initial categorization.Issue needs maintainer review and initial categorization.

   on Sep 8, 2026
4. juliusmarminge commented on Oct 22, 2026

   

   juliusmarminge

   on Oct 22, 2026 – with GitCafe Production

   Member

   More actions

   Reproduced on Linux in the web dev app at ed9b7ca9c5, using Claude Code 2.1.303 with explanatory-output-style@anthropic-plugin-directory enabled locally and the reported prompt. Insight fences render as inline code, with explanatory text running into the rules instead of a separate block.

   Existing fix candidate: #22239. No competing PR opened; leaving this issue open pending that work. Its fix has not been independently verified here.

   
5. juliusmarminge

   closed this as completedin #22239on Nov 11, 2026