TTSR on DeepSeek V4.1 Flash (thinking max): DSML leak misclassified as collapse-repetition, and the 'once' rule bricks the session #4621

Summary

On DeepSeek V4.1 Flash at thinking level max, the collapse-repetition stream rule fires repeatedly. Because the rule corrects only once per session (repeatMode: "once", nudgeKey: "collapse-repetition"), every turn after the first correction ends immediately with ttsr-loop-stopped and no recovery attempt, so the session becomes unusable. Reported in detail by a community member in code-yeongyu/oh-my-openagent#11610 (thank you, @asmond-lab).

Evidence (from the report)

• omo 5.1.46 (engine senpi 2026.10.23-1), desktop on Windows; several routes to the same model family.
• 21 collapse-repetition triggers and 8 hard stops across 6 sessions, all at thinking max.
• The model emits DeepSeek DSML tool-call envelopes (<｜DSML｜ invoke …>) inside thinking. The runtime keeps them, and later output imitates them until it collapses.
• The control-token-leak detector does not recognize DSML tokens, so the leak is classified as collapse-repetition instead of going to the resample path.
• The same session-ending pattern also occurs in threads with no DSML at all.
• The desktop launches the runtime with fixed arguments, so a user has no way to pass --ttsr-disabled.

Related

code-yeongyu/oh-my-openagent#11610 (report), #3883 (bracket/known-control evidence vs collapse classification), #4537 / #4538 (repetitive-turns pausing productive turns).

Acceptance criteria

• DeepSeek DSML envelopes in thinking are stripped (or never persisted/echoed), test-proven with a recorded stream shape.
• The control-token leak classifier recognizes DSML special tokens and routes them to resample, not collapse-repetition (test).
• A "once" stream rule can never brick a session: after the one correction, later turns get bounded recovery (e.g. a fresh correction budget per user turn, or a resample) instead of an immediate ttsr-loop-stopped on every turn (test covering the repeated-trigger sequence).
• Hosts that launch the runtime with fixed arguments (desktop) can still turn TTSR rules off or down through a setting.