test(scale): certify the Fly S26 billion-edge round trip

[DecisionNerd]

Problem

Component tests and laptop observations cannot establish the final billion-edge outcome. The integrated tree needs one reproducible provider-native proof of construction, recovery, queries, portable-v2 verification, clean import, reopen, and exact evidence across a progressive ladder.

Objective

Accept the terminal S26 result from the completed disposable Fly ladder in #900 as GraphForge's final billion-live-edge certification evidence.

Required ladder

S18 -> S19 -> S20 -> S22 -> S24 -> S25 -> S26

• Every rung uses the same frozen commit, immutable image, generator identity, EF16, seed, public lifecycle, durability, queries, and evidence contracts.
• Each rung generates its canonical deterministic dataset once and reuses those exact bytes throughout that rung. Smaller rungs are not derived by truncating or remapping larger-scale data.
• The Mac is control-plane-only and contributes no scale measurements.
• A failed rung authorizes no larger rung.
• S20 requires adjacent S18/S19 admission; S26 requires adjacent S24/S25 admission.

Certification requirements

• Identify the exact commit, OCI digest, Fly region, Machine class per rung, 500 GB volume configuration, OS/tool versions, profiles, seed, and maximum-scale authorization.
• S26 must produce >=1,000,000,000 live persisted edges after rejects/duplicates/self-loops are reconciled.
• Complete generate, ordinary staged construction, atomic publication, reopen/recount, deterministic one-hop/two-hop ordered-LIMIT queries, portable-v2 export, full integrity/compatibility verification, clean import, imported reopen/recount, and matching post-import queries.
• Record per-phase BenchExec wall/CPU/process-tree RSS/physical I/O and GraphForge logical construction/storage/reader/publication evidence.
• Prove bounded or plateauing RSS across the ladder. Persistent graph size is expected to be disk-bound; material edge-proportional RSS growth is a failure.
• S20 must fit the four-hour and 4 GiB envelope with reasonable headroom.
• Every rung must fit the four-hour runaway envelope. S26 must be admitted below the Fly 500 GB maximum with a 15% reserve (<=425 GB projected transient peak).
• Select the smallest Machine with measured headroom. Peak RSS <=128 GiB remains only an absolute M5 ceiling, never a sizing target or default.
• Reconcile source/imported counts, query observations, semantic package digest, transport digest, source generation, imported generation, and canonical fingerprints.
• Preserve prior CURRENT under cancellation, corruption, resource failure, or interrupted finalization; run negative drills at representative bounded scale.
• Validate closed sanitized evidence independently and check it into a durable reviewable repository location without large data or secrets.
• Prove complete teardown of Fly Machine(s), volume, app, image attachment, secrets, and temporary token material.

Acceptance criteria

• test(scale): complete the Fly S18-S26 lifecycle ladder #900 provides complete passing S18-S26 ladder evidence with every authorization gate preserved.
• S26 live persisted edge count is independently >=1,000,000,000.
• Full portable-v2 verification precedes clean import, and source/imported reopen results match.
• Required query observations and canonical fingerprints match before and after import.
• All per-phase resource and product counters are present, reconciled, sanitized, and schema-valid.
• Every rung stayed within its declared envelopes, or this issue remains open with the first failure documented.
• Complete Fly teardown is independently proven.
• Final evidence/docs PR has exact-head green CI and CI Gate.

Non-goals

A benchmark leaderboard, laptop certification, universal hardware-independent capacity claims, a 24-hour normal-usage story, uploading the billion-edge payload to a registry, or accepting a skipped/interrupted rung.

Relationships

• Execution close gate: test(scale): complete the Fly S18-S26 lifecycle ladder #900
• Harness epic: epic(bench): externalize scale certification and add GDC benchmark suites #952
• Portable-v2 conformance: epic(io): ship portable project v2 packaging verification and promotion #740