Charley Cunningham c3cb38eafb Clarify cumulative proposed_plan behavior in Plan mode (#12265) ...

## Summary
- Require revised `<proposed_plan>` blocks in the same planning session
to be complete replacements, not partial/delta plans.
- Scope that cumulative replacement rule to the current planning session
only.
- Clarify that after leaving Plan mode (for example switching to Default
mode to implement) or when explicitly asked for a new plan, the model
should produce a new self-contained plan without inheriting prior plan
blocks unless requested.

## Testing
- Not run (prompt/template text-only change).

2026-02-19 12:18:23 -08:00

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default.md

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execute.md

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pair_programming.md

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plan.md

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