Decide #310's data-authorability fork as (b), split by run-mode
authority: selecting a Named fold subscription is data-reachable on the
one-shot run path; adding a fold stays a Rust entry (role 2, C25).
`aura run` gains a repeatable --tap TAP=FOLD selector feeding the
existing TapPlan seam: no flag keeps the record-all default; any flag
replaces the plan entirely (unlisted taps stay unbound — C27 inert,
non-error). Validation stays in bind_tap_plan (roster-enumerating label
refusal, typed UndeclaredTap, both before store I/O); parse-level
refusals (malformed pair, duplicate tap) exit 2 via the verb's usage
convention.
Rejected alternatives (minuted on #310 with the skeptic-pass
rationale): an op-script/blueprint carrier (C27 forbids recording
policy in the serialized fragment); ratifying Rust-only (softens a
designed-in promise with effort as the only rationale). The
campaign/document carrier and the persist_taps/declared-tap namespace
reconciliation are deferred to the Measurement-reachable milestone
(#312/#327, minuted on #312).
Ledger: C27 Current state records the boundary; the superseded sentence
moved verbatim to the new c27-declared-taps.history.md sidecar; the
glossary tap-plan paragraph updated, fixing the pre-existing inaccuracy
that named `aura measure` a record-all-passing verb (it is the post-hoc
IC analysis and constructs no tap plan).
Verification: 5 new unit tests (parse branches), 5 new binary-level
selector tests incl. a byte-identity pin of an explicit all-record plan
vs the record-all default (C1), 1 measurement-arm test; full workspace
suite green; clippy -D warnings clean. Independent opus diff review:
approved, no Important/Minor findings (nits: inert-arm generic refusal,
a=b=c falling to the roster refusal — accepted as-is).
closes#310
Phase 3 of the Stratification milestone (contract C28). `aura run` now
shape-dispatches on the loaded blueprint: a `bias` output takes the
existing strategy path (wrap_r + R evaluation), byte-identical; a
blueprint that declares taps but exposes no `bias` runs bare via the new
`run_measurement` (bootstrap, run, drain the declared taps) with no
SimBroker, no risk executor, and no per-cycle equity/exposure/r
recorders; a blueprint exposing neither is refused. This gives the
measurement layer its own run verb and removes the O(cycles) recording
retention (the measured ~2 GB peak RSS over 12y UK100 M1) the mandatory
R scaffold imposed on a measurement-shaped run.
A new `MeasurementReport { manifest, taps }` (aura-engine::report, beside
RunReport) is the stdout/record shape — no R metrics, since a bare run
has no broker. The manifest's `broker` carries an interim "measurement"
sentinel; the honest `Option<String>` model is deferred to the #147
metric-genericity block, keeping this phase #147-free and the
strategy-path C18 goldens byte-identical.
`run_signal_r` is untouched (the tap machinery is duplicated into
`run_measurement`, not extracted). The measurement arm's closed-blueprint
guard uses `signal.param_space()` rather than `blueprint_axis_probe`,
which welds wrap_r and would panic on a no-`bias` signal.
refs #286
claude