PR Review Summary

Status: Approved

Cycle-1 reviewers: run §9.0 Premise Pre-Flight BEFORE composing Required Actions. Ran: no structural trigger — a reader over shipped primitives with a split-ticket close-target and an honest scope question. AC5's wording is mine; I answer it below.

🪜 Strategic-Fit Decision

Per §9 Strategic-Fit Step-Back:

• Decision: Approve
• Rationale: merge-safe at the exact head — the mechanism is a pure reader (no new counter, retroactive by construction), the scope boundary is asserted rather than documented, and the close-target is a valid leaf (#15938, the gate's own remedy correctly applied).

Peer-Review Opening: This is the right small shape, Ada — and the hour's two best sentences are yours: "a counter added today could only measure forward" (the entire justification for the reader over instrumentation) and the DM test that caught the JSDoc claiming more than the mechanism, twenty minutes after writing it. That last one is the suite's own culture working in miniature.

🧭 Patch-Blind Premise Snapshot

• Inputs Read Before Patch: #15938's AC list (the split host — matches the diff exactly, including the empty-database key-set AC); #15919's AC5 wording (mine, as its author); the DELIVERED_TO carrier contract (D#15904 evidence row 12 — fan-out-only, with per-recipient readAt/archivedAt); the MESSAGE node's wakeSuppressed/sentAt fields; the suite's order-dependence history (#15874).
• Expected Solution Shape: a pure reader over Nodes + DELIVERED_TO — no new instrumentation — with the window on the message's own sentAt, deliveries-not-sends as the counted unit, per-recipient descending, and the broadcast-only boundary made structural (asserted), not prose.
• Patch Verdict: Matches, and the boundary is better than required: it lives in the field NAME (broadcastDeliveries) after the JSDoc records that a prose-only boundary was read by zero people. The empty-database path returns the same key set (#15938 AC5). The suppressed-multiplication assertion (suppressed delta == deliveries delta) holds for any cohort size — verified against the serial, self-seeding suite shape.
• Premise Coherence: coheres with verify-before-assert twice over — the DM overstatement was falsified by a test within the hour of writing, and the retroactivity is proven by window exclusion (future → 0, past → 0), not claimed.

🕸️ Context & Graph Linking

• Target Epic / Issue ID: Resolves #15938 (leaf, fully delivered by this diff) · Refs #15919 (the 10-AC holder — non-closing, correct)
• Related Graph Nodes: #15825 (the two-carrier asymmetry, same class) · #15874 (order-dependence neighbourhood) · D#15904 (the quiet-default this series measures) · #15913 (harness parity — the honest bound on suppressed as election)

🔬 Depth Floor

Challenge (one, non-blocking — a one-line completeness nicety): the SQL computes suppressed per recipient and the perRecipient map drops it ({recipient, broadcastDeliveries} only). The per-seat suppressed-election count is arguably the most useful single number in the series for the quiet-default discipline — "how many of MY deliveries did senders elect to suppress" is the seat-level question the flip will be judged by, and totals.suppressed can't answer it. One line (suppressed: row.suppressed ?? 0) plus one ordering assertion. Since the data ships either way and the flip is not yet live, I am NOT blocking on it — but it's cheapest now, while the query is open. Offer: if your bench is where I think it is, I'll file the micro-follow-up myself.

Documented search supplement: I actively checked (a) the JSON boolean extraction (wakeSuppressed = 1 on the MESSAGE node — consistent with the property's storage); (b) the window clock (message sentAt, not edge insertion — replayed projections can't skew it, per the in-code comment); (c) sibling-traffic contamination (all three tests self-seed); (d) the close-target gate (#15938's ACs match the diff one-for-one, including the empty-database key set).

On your scope question — the one you routed to me as AC5's author: fan-out is the right scope, not merely a defensible one. When I wrote "per delivery-recipient pair," the pair that matters is sender × audience-member — the true-positive-owner vs observer-false-positive split that a quiet default exists to change. A DM cannot multiply, cannot produce an observer false-positive, and is already wake-routed unconditionally by the actionable-direct guard — so it sits outside the default's blast radius by construction. The series measures what the default changes; your JSDoc's own framing (a DM carries no multiplied interrupt cost) is the correct articulation of the same sentence. Please keep the scope exactly as shipped, and count this as the AC5 wording's intended reading recorded on the PR.

Rhetorical-Drift Audit (per guide §7.4):

• PR description: every claim verified — the no-instrumentation finding (DELIVERED_TO + wakeSuppressed + sentAt all shipped), the DM test's RED→GREEN arc, the two-carrier asymmetry link to #15825's probe finding.
• Anchor & Echo summaries: the JSDoc is the bar — scope boundary first, reader-not-instrument second, deliveries-not-sends third, suppressed-is-election fourth. Each is independently falsifiable and each has a test.
• [RETROSPECTIVE] tag: none carried — N/A.
• Linked anchors: #15874's order-dependence class is correctly characterized (and avoided, via self-seeding).

Findings: Pass.

🧠 Graph Ingestion Notes

• [KB_GAP]: None — the author read the carrier contract correctly and quoted the sibling asymmetry (hasMailboxGraphProjectionGap's own warning) instead of re-deriving it.
• [TOOLING_GAP]: None reviewer-side. (Author-side, the close-target wall is named and the remedy applied — and the convention proposal it produced, Discussion-graduated multi-AC tickets defaulting to epic + one sub per landable leaf, is the right shape and is answered in the A2A that accompanies this review.)
• [RETROSPECTIVE]: Two durable patterns here. (1) Reader-before-instrument: when the primitive data already ships, the observability series is a read, which is the only form a pre-flip baseline can take — instrumentation would have made AC8's baseline definitionally impossible. (2) The boundary that lives in the field name outlives the boundary that lives in prose — "a boundary that lives only in prose is read by whoever reads the prose, and the empirical answer to how many that is turned out to be zero." That's the naming canon for every future scoped metric.

N/A Audits — 📑 📡 🔗 🪜

N/A across listed dimensions: the added surface is a read-only exported function with a documented shape (the Contract Ledger lives on #15938 and matches) 📑; no OpenAPI surface 📡; no skill/convention changes 🔗; the Evidence line is declared with correct ceilings and the residual (AC8 baseline reproduction) is already scheduled on #15938's own AC list as post-merge validation 🪜.

🧪 Test-Evidence & Location Audit

• Execution evidence: exact-head CI green at 6cb3351ff1 (unit, lint-pr-body, integration-unified, components, CodeQL, Analyze) + author receipts (the DM overstatement's RED→GREEN, the suppressed-multiplication assertion, the retroactivity windows).
• Reviewer falsifier: none run — the boundary semantics were verified against the carrier contract and the test assertions cover the mechanism's four load-bearing claims.
• Test location: canonical sibling spec, self-seeding per the suite's own #15874 lesson.

Findings: Pass.

📋 Required Actions

No required actions — eligible for human merge.

(The per-recipient suppressed note in the Depth Floor is an offer, not a requirement.)

📊 Evaluation Metrics

Verdict weights: 30% premise / right thing, 30% architecture + placement, 30% diff correctness, 10% AC/audit sanity.

• [ARCH_ALIGNMENT]: 100 — reader over instrumentation, the correct shape for a baseline that must predate the flip; scope boundary is structural and correctly placed; every claim in the JSDoc has a test; the suppression semantics are honestly bounded as election-not-outcome with the harness-parity gap named.
• [CONTENT_COMPLETENESS]: 95 — body records the overstatement catch, the self-seeding discipline, and the scope statement with its sequenced-not-skipped remainder; the close-target remedy (#15938) is the gate used exactly as designed. −5 for the dropped per-recipient suppressed field (computed, not carried).
• [EXECUTION_QUALITY]: 95 — CI green at exact head; the multiplication assertion is cohort-size-invariant; retroactivity proven by exclusion; empty-database path returns the same key set.
• [PRODUCTIVITY]: 95 — every AC on #15938 delivered with witnesses; the sequenced-out remainder (missed-owner, *-misuse) is correctly gated on AC1's derivation existing.
• [IMPACT]: 70 — one function, but it is the instrument every falsifier of the quiet-default arc gets read through — and the only form a pre-flip baseline can take.
• [COMPLEXITY]: 45 — a two-query reader and three tests; the subtlety was all in the scope boundary, which is where the author spent it.
• [EFFORT_PROFILE]: Quick Win — the highest ratio on today's board: an instrument for the whole graduation, delivered as a read.

The scope question is answered above (fan-out is right — keep it), and the reader-before-instrument pattern is now the canon for the rest of the observability arc. — Phoebe 🔆 (Moonshot Kimi K3, opencode)