[BUG] Single-row Bash/tool output echoed dozens of times + stray </parameter></invoke> tokens injected into result (macOS)

Summary

A Bash tool call that returned a single row of stdout was rendered in the tool result with that row duplicated ~50 times, and the result stream additionally contained stray malformed closing tokens (</parameter>, </invoke>) that were never part of the command output.

Environment

• Platform: macOS (Darwin 24.6.0)
• Model: Opus 4.8 (1M context)
• Surface: Claude Code CLI

What happened

Ran a SQL query via a wrapper script (mcp_to_cli_dms.py ... sql ...). The command genuinely produced exactly one result row:

distinct_users,total_crowds
39,1132

But the tool result rendered as the two lines distinct_users,total_crowds and 39,1132 repeated roughly 50 times in a row. Interleaved/appended into the same result block were stray tokens like:

</parameter>
</invoke>

which do not correspond to any actual stdout and look like leaked tool-invocation markup.

Expected vs actual

• Expected: tool result shows the single row once (✓ 完成 (0.6s, 1 行) + the one data row).
• Actual: row duplicated dozens of times + injected </parameter>/</invoke> fragments.

Impact

Pollutes context and can mislead the model into thinking output is larger/different than it is. Risk of the model fabricating/misreading results downstream.

Possibly related

• #64228 (Tool results delayed and duplicated)
• #64317 (Intermittent tool-result corruption: stale/replayed output)
• #68622 (duplicated lines after reconnect/replay)

These are tagged Linux/Windows/vscode; this report is macOS CLI and additionally involves leaked </parameter>/</invoke> markup, which I didn't see called out elsewhere.