claude
9f87e5a583
Architect review over 9636b00..9221bcd. What holds, confirmed against the diff rather than the commit body: no stored record shape moved (neither `aura-engine/src/report.rs` nor the registry compat mirror appears in the change at all, and the byte pins pass unedited); the handle travels the beside-the-report route C27/#297 established for the unbound-tap names, with the library still printing nothing; trace enumeration landed inside `aura-registry` where C22 puts trace file I/O; no C14 exit class moved, both refusal arms falling through to the same exit 1. Two high drift items, both fixed here: - The corrected refusal claimed a campaign run prints its handle as `trace_name` on stdout. It prints `campaign_run.trace_name` — the campaign leg wraps its record, as the glossary states outright — so the chain the refusal advertised returns null there. This is the third instance of one error class in this cycle: a false claim inside the very prose meant to stop misdirecting callers. Grounding caught the first two, review the third. - The measurement leg shipped without the handle pin the spec asked for. All three new pins drove the strategy path, so the measurement leg emitted a handle nothing asserted. It has its own test now, on the shared bind pair the two legs cannot drift across. Ledger and vocabulary brought into lockstep: C27's current state records the `RunOutcome` carrier that replaced the pair; the glossary's tap entry names the single-run handle and warns that a family id is not one; the authoring guide's own single-run tap example now says the name is printed rather than guessed. The suggestion line gained the `aura:` prefix every other stderr line carries. Bench: all five fingerprints OK — the decisive signal, since they hang on the record bytes this cycle was required not to move. Timing deltas are load noise (loadavg 8.7 under concurrent agents), not regressions. refs #309
8.5 KiB
C27 — Declared taps: named measurement points bind sinks run-mode-aware
Guarantee. A blueprint may declare taps — named, pure output-side
declarations { name, from: {node, field} }, the output-side twin of input_roles
(C26). A tap names an interior producer's output field
without naming a sink, exactly as a Role names an abstract input without naming a
source. At compile the tap resolves — and, for an interior composite, hoists to
the root — through the same lowering remap edges and OutField re-exports use
(resolve_tap_wire, a flat_taps accumulator threaded through the lowering
recursion), landing in FlatGraph.taps as a FlatTap { name, node, field } whose
name survives compile and is load-bearing for by-name binding (like
SourceSpec.role, #275).
Binding is run-mode-aware: the run-mode-owning layer constructs a consumer at
a bound tap via FlatGraph::bind_tap, which takes a caller-built
Box<dyn Node> sink (so the engine keeps its aura-core-only production
dependency — it never constructs a domain sink type) and appends it plus an edge
before bootstrap. What consumes a tap is declared per run by a tap plan
(#283): a Named { label, params } subscription resolves against a layered
fold registry (core vocabulary record | count | sum | mean | min | max | first | last; growth is a new Rust entry, C25, injectable by higher layers
without a core edit), and Live(closure) is the single deliberately non-data
variant. Both declared-tap entry points — the single-run path (run_signal_r)
and the bare measurement path (run_measurement) — bind through one shared
wiring pair, so they cannot drift: record persists the full series at constant
memory through the trace store's streamed write path (env.trace_store()), folds
keep an O(1) accumulator and land one summary row at finalize, so the tap columns
surface through the same tooling the campaign path feeds; a sweep/reduce run
leaves taps unbound.
Forbids. A tap carrying a channel endpoint or effect in the serialized artefact
— recording policy is run-mode authority, not fragment-embedded (a fragment must
not drag its measurement decisions into every harness that embeds it; the tier
ontology, C20/C21). The engine
constructing a domain sink type (the aura-core-only wall — the sink is
caller-built). Order statistics (median, etc.) inside the graph — they stay
sink/analysis-side (C18); multi-instrument study
inputs stay harness/World tier.
Non-error. An unbound tap is inert, not a fault — unlike an unbound root
input role, which check_root_roles_bound rejects (C26):
observation is optional, a fed input is mandatory. A declared-but-unbound tap
compiles and runs, its producer evaluating and its output discarded (a no-out-edge
producer is a valid runnable sink — the Kahn sort emits it,
check_ports_connected gates only inputs). The CLI surfaces this to the human
as a note (aura: note: declared tap "…" unbound this run) printed from the
unbound names the entry points return beside their report — never emitted by
the library itself (#297).
Why. Observability must be expressible in a hand-authored blueprint — the measurement-shaped study computes in the graph and surfaces via taps, no throwaway Rust harness — while recording stays a run-mode decision, not a fragment-embedded effect. Taps are designed DCE-compatible (a bound tap is a natural DCE root, an unbound tap a dead declaration) but this contract does not depend on DCE: an unbound tap's sink is simply never constructed (build-time elision, which the engine already tolerates). (#282, 2026-07-18.)
Current state
The tap types are realized in aura-engine: the authoring-level Tap
(crates/aura-engine/src/blueprint.rs, the output-side twin of Role), the
compiled FlatTap { name, node, field } and the FlatGraph.taps field
(crates/aura-engine/src/harness.rs), and FlatGraph::bind_tap, which appends a
caller-built Box<dyn Node> sink plus an edge and raises a typed UndeclaredTap
on a tap the graph does not declare (duplicate detection across binds is the
caller's — the method keeps no cross-call state). Lowering resolves and hoists taps
via resolve_tap_wire and the flat_taps accumulator (blueprint.rs). The
subscription seam is aura-runner::tap_plan (#283): TapPlan/TapSubscription,
the layered FoldRegistry (each entry carries a doc line — the help surface
and the roster-enumerating refusal — plus a scalar-typed param schema; all core
entries are param-less today, the seam ships in every entry's build signature),
and the shared bind_tap_plan/BoundTaps pair called by both declared-tap entry
points, run_signal_r (aura-runner::member) and run_measurement
(aura-runner::measure) — both arms of the single CLI verb aura exec (#319),
whose repeatable --tap TAP=FOLD selector (#310) makes the Named selection
data-reachable: no flag keeps the record-all default, any flag replaces the
plan entirely (unlisted taps stay unbound/inert). BoundTaps carries the
unbound tap names out (skipped: Vec<String>), riding beside the returned
report rather than inside it, so the CLI — not the library — prints the
unbound-tap note (#297). Since #309 both entry points return that pair as a
named RunOutcome { report, skipped, trace_name }, the third field being the
trace-store handle the run recorded under (Some under exactly the condition
that opens the write path, None otherwise) — the same beside-the-report
discipline, widened rather than re-cut: the record keeps its shape and the
shell renders the handle. The boundary is thereby
fixed in place: selecting a subscription is run-mode authority, exercised
by the run-mode owner — on the one-shot path the CLI invocation itself, a
projection exercising this contract's authority, not a second home for
intent under C25 — while adding a fold stays a Rust
entry (role 2). The campaign/document carrier, and the reconciliation of the
presentation-tap namespace (persist_taps) with declared taps it requires,
is deferred to the Measurement-reachable milestone (#312/#327, minuted on
#312). The record
consumer (aura-runner::tap_recorder::TapRecorder) holds the trace store's
streaming writer in-graph — initialize opens (deferred acquisition), eval
appends (Timestamp, Cell) (zero per-cycle heap, #77), finalize reports
exactly one terminal outcome; fold consumers (aura-std::TapFold) land one
summary row, emitted at finalize and stamped with the instant of the last
contributing (warm) value — first alone pins the first contributing
instant; min/max deliberately do not carry the extremum's timestamp (a
whole-window row privileges no interior instant) — ratified as-is, #335;
live closures run inline
(aura-std::TapLive). The sweep/reduce
path never calls bind_tap.
The chain-pruning benefit — a sweep paying zero for the study wires behind an unbound tap — is deferred to the future DCE cycle (C23); the mechanism ships now, verified sound.
#337 (2026-07-26 harvest) ships the positive discovery view:
Composite::declared_taps() (crates/aura-engine/src/blueprint.rs) walks the
blueprint depth-first collecting (tap name, source wire, column kind), bare
at every depth, bounds-total over an invalid wire; graph introspect --taps <FILE|ID> renders one row per declared tap (a tap-less blueprint is a
stderr-noted listing, exit 0). This closes the recovery-only discovery
gap: before #337, the only way to learn a blueprint's declared tap names was
provoking bind_tap_plan's UnknownTap refusal roster (#333) — a real name
surfaced only as the side effect of naming a wrong one first. The refusal
roster itself is unchanged and remains the recovery half (what to do once
a tap name is already wrong); --taps is the discovery half (learning the
right names up front).
See also
- C26 — the input-side twin (
input_roles);check_root_roles_bound, the mandatory-input counterpart - C23 — compilation/lowering and the deferred DCE cycle the tap design anticipates
- C18 — the trace store and registry the tap series feed; order statistics live sink-side
- C20, C21 — the tier ontology behind run-mode recording authority
- C8 — the node/sink contract (a no-out-edge producer as a valid runnable sink)