[TheGreatAxios]

Summary

• Coder spawns at max V4 reasoning effort, matching the other orchestrators, instead of the cheapest low/none rung (CL-10311).
• Off-ladder V4 reasoning efforts (anything but none/xhigh/max) arriving on a manual, exec, or config path are rejected with a clear error rather than coerced or passed through to the wire (CL-10312).
• The DeepSeek family predicate matches the whole deepseek line (deepseek, deepseek-v4, deepseek-chat, deepseek-coder, deepseek-v3, and org-qualified ids), so the adapter router, effort routing, and model-family key treat pre-V4 and V4 DeepSeek consistently (CL-10313).

Verification

• bun run check passes: lint, typecheck, check:dead-exports, and build all green; guarded tests 8571 pass / 1 fail.
• The single test failure is the known pre-existing src/shell/literal-path-arguments.test.ts "allows: cat .ENV" case, which also fails on clean main and is unrelated to this change.

Fixes CL-10311
Fixes CL-10312
Fixes CL-10313

[linear-code]

CL-10312

CL-10313

CL-10311

[TheGreatAxios]

Superseded by #1384 (head branch renamed to the Linear gitBranchName).