René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Stray \"x\" appears at the end of every prompt (leftover Claude Code 0.2.70 workaround)","articleBody":"## Summary\n\nEvery message sent through agentapi to Claude Code produces a visible stray `x` character in the prompt area. The `x` comes from a workaround introduced in [b732081](https://github.com/coder/agentapi/commit/b732081cbbe11a97fcbe1ac772b3a0fd80f36547) almost a year ago, which the commit itself promised to remove \"a couple of days after the new version is released.\"\n\n## Source of the bug\n\n`lib/httpapi/claude.go`, in `formatClaudeCodeMessage`:\n\n```go\n// janky hack: send a random character and then a backspace because otherwise\n// Claude Code echoes the startSeq back to the terminal.\n// This basically simulates a user typing and then removing the character.\nparts = append(parts, st.MessagePartText{Content: \\\"x\\b\\\", Hidden: true})\n```\n\nThe hack was a workaround for a bug in Claude Code 0.2.70 (anthropics/claude-code#803). With current Claude Code versions, the bracketed-paste start sequence is no longer echoed, so the masking `x` is rendered straight into the prompt area and the `\\b` has nothing to erase — net result is a visible `x` on every message.\n\n## Environment\n\n- agentapi **v0.12.1** (latest release as of writing)\n- claude-code **2.1.143**\n\n## Notes\n\n- PR #208 (merged 2026-04-10) touched this same file but only added a doc comment to `formatPaste`; the `x\\b` line was left in place.\n- Possibly related to #207 (\\\"Claude Code 2.1.83 breaks terminal capture\\\") — both look like consequences of Claude Code's rendering pipeline no longer behaving the way the 0.2.70-era workarounds assumed.\n\n## Proposed fix\n\nRemove the `parts = append(parts, st.MessagePartText{Content: \\\"x\\b\\\", Hidden: true})` line. The original Claude Code bug it worked around is long fixed.","author":{"url":"https://github.com/mzihlmann","@type":"Person","name":"mzihlmann"},"datePublished":"2026-05-18T09:00:30.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/223/agentapi/issues/223"}