The :tools model suffix engages NanoGPT's server-side tool-call parser,
which 502s with code malformed_tool_call on complex DeepSeek payloads
(observed reliably on todo_write). The default route forwards
delta.content (including DSML envelope leaks) which our StreamMarkupHealing
already heals into a structured tool call.
The DSML allowlist still covers nanogpt and the parallel-index fix
remains; only the :tools suffix is removed.
Fixes#1488
roboomp
7d3476216a