code-modernization: pilot-first uplift migration, brief-driven execution, deeper preflight

/modernize-uplift migrates one representative project end-to-end and
writes its lessons to analysis/<system>/PLAYBOOK.md before touching the
rest. The remaining projects then fan out through a new uplift-migrate
workflow, one uplift-migrator agent per project, in dependency-aware
escalating batches behind a per-batch circuit breaker. A recorded
per-test baseline (analysis/<system>/BASELINE.md) gates the migration,
and the delta catalog reports a test framework whose runner does not
support the target as its own highest-blast-radius dependency.

The three execution commands (uplift, transform, reimagine) read
MODERNIZATION_BRIEF.md and treat their phase's scope and entry and exit
criteria as gates, so editing the brief steers execution. For a
same-stack uplift the brief requires the delta catalog and applies the
same ordering overrides the execution command does.

/modernize-preflight opens with a short interview (scope, local build
and test, bespoke build infrastructure, prior attempts, what is off
limits) without blocking on the answers, reads the CI/build definition
for how the system builds, escalates the smoke test to a whole-project
restore and build, and adds a scope-boundary check that enumerates
inbound and outbound dependencies when the system directory is a slice
of a larger repository.

Workflow scripts accept args delivered as either a JSON string or an
object.

plugins/code-modernization/commands/modernize-transform.md

@@ -37,6 +37,18 @@ first run:
 
 ## Step 0b — Plan (HITL gate)
 
+**The brief is binding — read it first.** If `analysis/$1/MODERNIZATION_BRIEF.md`
+exists, this transform is one phase (or one module of a phase) of that plan:
+read it before deciding anything below. Find the phase that names this
+command with `$2` in scope, and treat that phase's **scope, entry criteria,
+exit criteria, and any edits the user made to it** as binding on the plan
+you present below. Entry criteria are *gates*, not context: if one is not
+met (a prior phase's exit criteria, an SME sign-off the brief requires),
+meeting it **is** the next step — do not proceed past it and do not silently
+re-plan around it. If the brief exists but no phase covers `$2`, stop and
+ask which phase this is. The user steers execution by editing the brief; a
+brief the execution command never reads cannot steer anything.
+
 Read the source module and any business rules in `analysis/$1/BUSINESS_RULES.md`
 that reference it. Then present the plan and **stop — write no code until
 the user explicitly approves** (use plan mode if the session supports it):