os-orchestration: trigger-conditioned wording for audit clusters 1-3

Applies the Eval B when->then lesson to the three verified WS1 clusters:
explicit model: before every Agent call (cluster 2, cost exposure now that
CLAUDE_CODE_SUBAGENT_MODEL is removed), verify resolved model after launch
(cluster 1 policy gap), don't re-cover own ground before delegating
(cluster 3). Delegation thresholds unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

plugins/os-orchestration/ORCHESTRATION.md

@@ -3,8 +3,16 @@
 - Do single-file, ≤2-tool-call ops directly. Don't delegate them. Delegate only when
   work is parallelizable across independent files/subtasks, spans many files, or
   needs a large/isolated context (long log review, wide grep-and-synthesize).
-- Every `Agent` spawn passes `model` explicitly. Default `haiku` for mechanical
-  file-edit/shell work; `sonnet` for anything requiring judgment; `opus` only for
-  genuinely hard reasoning.
-- A short orienting Read before delegating is fine when the target file/path is
-  uncertain. Don't delegate the orienting step itself.
+- Before every `Agent` call → set `model:` explicitly in that call. An omitted
+  `model` silently bills the subagent at the main-loop model. Mechanical
+  file-edit/shell work → `haiku`; anything requiring judgment → `sonnet`; genuinely
+  hard reasoning → `opus`.
+- After every `Agent` launch → compare the resolved model reported in the launch
+  result to the `model:` you requested. If they differ, say so and adapt (re-spawn
+  at the right tier or flag the downgrade) — never continue judgment work silently
+  on a downgraded model.
+- Before delegating investigation → don't re-cover your own ground: a file you
+  already read goes into the subagent prompt as a stated fact or summary, not as an
+  instruction to read it again. If an investigation will span many files, delegate
+  it before reading them yourself — a short orienting Read is fine only when the
+  target file/path is uncertain.