bug: tmq re-dispatch silently reuses stale session command — new --provider/--model ignored

[jakecelentano]

Scope

tmq <repo> <issue> re-dispatch silently reuses the previous session's command — new --provider/--model flags are ignored when an aoe registration for the session title survives.

Repro (2026-07-20, feat-openagent#66):

1. Original dispatch: tmq openagent 66 --agent pi --provider minimax --model MiniMax-M3 → session command carries MiniMax.
2. Session hung; operator ran aoe session stop feat-openagent#66 (stop, not remove).
3. Re-dispatch: tmq openagent 66 --agent pi --provider deepseek --model deepseek-v4-pro → tmq printed the normal "Spawned:" output, but aoe session show revealed the command was STILL pi --provider minimax --model MiniMax-M3 .... The wrong model ran for ~45 minutes before the mismatch was noticed via the pane's model indicator.
4. Workaround that fixed it: aoe rm feat-openagent#66 --purge before re-dispatching — then the new flags took.

Root cause hypothesis: the deployed bash tmq's aoe rm --purge step before aoe add either fails silently or is skipped when the session exists in stopped state, so aoe add no-ops ("Session already exists with same title and path") and session start revives the stale command. The Python plugin (bogocat/tmq spawn.py) has the same rm→add→start sequence — verify whether it fails the same way.

Why it matters

Redispatch-after-kill is the standard recovery move for hung agents (twice today). A silent model/provider mismatch corrupts routing decisions AND provenance: the dispatch event logs the requested model while the served model differs — exactly the class of gap tms#74 and distillery's served-model provenance work exist to prevent.

Acceptance criteria

• Re-dispatch over an existing (stopped or running) same-title session either fully replaces the registration (rm --purge that verifiably succeeds) or fails loud with instructions — never silently reuses the old command
• Regression test: dispatch, stop, re-dispatch with different --model; assert the session command contains the new model
• Same check ported to / verified in the Python plugin (bogocat/tmq)
• Dispatch event row logs the command actually installed, not just the requested flags

References

• 2026-07-20 wave: feat-openagent#66 double-dispatch incident (this issue's repro)
• tms#74 (provider-only dispatch can log mismatched default model — sibling provenance gap)
• bogocat/tmq spawn.py:151-183 (rm→add→start sequence in the Python port)