merge origin/main into feat/wf5-securestorage

Brings MOSAIC_GIT_IDENTITY (per-seat git authorship) onto the delivery
branch, which had none of it. The branch carried W-F7's FLEET_SEAT seam in
the same launcher file; the two auto-merged cleanly.

Three single-hunk conflicts resolved:
- pr-merge.sh: kept branch policy allowing main OR next (next is the
  release stream).
- test-ci-queue-wait-tristate.sh: kept the branch's 4 added merge-readiness
  assertions; merge base and main both had zero, so nothing of main's is
  reverted.
- package.json test:framework-shell: union of both enumerations, 50 entries,
  no test dropped from either side. Picks up main's test-start-agent-session.sh
  and test-fleet-units.sh, which are the guards for the identity key.

packages/mosaic/framework/defaults/STANDARDS.md

@@ -60,6 +60,52 @@ If a repo does not expose these scripts, run equivalent local workflow commands
 - Do not auto-resolve data conflicts in shared state files.
 - Keep commits scoped to a single logical change set.
 
+## Model Tiering
+
+Model choice is a standard, not a preference. Delegating a mechanical grep to a
+frontier reasoning model wastes budget; sending a security review to a cheap tier
+produces a review that passes and proves nothing. Both are defects.
+
+Tiers are named by **capability class**, so the standard survives a model
+generation. An operator binds each class to a concrete model id.
+
+| Class         | Use for                                                                                   |
+| ------------- | ----------------------------------------------------------------------------------------- |
+| `search`      | grep/glob, file location, status and health checks, one-line mechanical edits             |
+| `build`       | feature implementation, test writing, bugfixes, routine refactors                         |
+| `judge`       | code review, planning, API/compat-sensitive changes                                       |
+| `adversarial` | security review, ambiguous architecture, anything where a wrong "looks fine" is expensive |
+
+Rules:
+
+1. **Start at the cheapest class that can do the task; escalate on evidence, not
+   on nerves.** Omitting a tier is not neutral — it inherits the caller's model,
+   which is usually the most expensive one.
+2. **Compat-sensitive work escalates one class.** A change that must interoperate
+   with an existing contract is judged, not just built.
+3. **A tier assignment is benchmarked, not asserted.** Move a task class to a
+   cheaper tier only against a blind A/B on real work from this codebase, ranked
+   by someone other than the author. "It seemed fine" is not evidence.
+4. **Reviewer independence beats reviewer size.** An `adversarial` verdict from
+   the model that wrote the code is not a second opinion (see Constitution gate 16).
+
+### Where the binding lives
+
+The class→model map is operator configuration, never framework source: model
+availability, cost, and quotas differ per operator and per host.
+
+Resolution order, first hit wins:
+
+1. the config service (DB-backed, surfaced and editable in the Mosaic webUI)
+2. a local operator file (`STANDARDS.local.md`, or `policy/` where the runtime
+   injects it)
+3. the framework default — the class names above, with no binding
+
+Only layer 1 is auditable across a fleet, so it is the target end state; layers 2
+and 3 exist so a host with no config service still runs. A local override that
+silently disagrees with the config service is drift — the same failure class the
+tool-index gate exists to catch, and it belongs in `mosaic doctor`.
+
 ## Prompting Contract
 
 All runtime adapters should inject: