test(core): CellScheduler scale probe — measure the O(n²) before refactoring - #9131
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…ctoring (shadow*) Follow-up #1 to the DBSP consumer (#9129): measure the deferred O(n²)-queue hot path instead of assuming it. Adds a scale probe (correctness-at-scale assertions are deterministic; wall-clock is informational only, NOT a DST proof). Measured at N=2000 (the adversarial cases): wide fan-out ≈59ms, deep chain ≈35ms — well within the design's stated "thousands of cells" target. The quadratic is real (fan-out ≈ O(N²) ⇒ ≈1.5s at N=10k) but does NOT bite at the target scale. Outcome: the ImmutableQueue + Set-membership refactor stays DEFERRED — now with DATA, not a guess. The measurement says it is not yet earned; earn it when a consumer targets ~5-10k cells. Updated the debt ledger §6a with the numbers. This is the razor-honest disposition: measure first, refactor only when the number justifies it. Also proves the scheduler is CORRECT at 2000 cells (nothing else exercised it beyond ~12) — a real gain regardless of the perf decision. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com> AgencySignature-v1: persona: otto actor: zeta-otto surface: tests topology: shadow-clone intent: cell-scheduler-scale-probe-measure-on2-hot-path-defer-with-data-not-guess authorization: aaron-standing-24h-autonomous-2026-07-02 uncertainty: low measure: scale-probe-n2000-fanout-59ms-chain-35ms-quadratic-real-but-below-target-refactor-deferred-with-data-correctness-at-scale-proven delta-u: replaces-perf-guess-with-measurement-defers-refactor-honestly-proves-correctness-at-2000-cells seed: S4
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| let n = 2000 | ||
| let sinks = [ for i in 1 .. n -> sprintf "s%04d" i ] | ||
| let cells = ("src", 0) :: [ for s in sinks -> s, 0 ] | ||
| let seed = [ "src", { D = 0; To = sinks } ] // src fans a message to every sink |
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Because this scale case seeds D = 0 and sends only one message to each sink, the later count/contains assertions would still pass if the scheduler dropped all emitted sink messages after initializing the cells. It also never exercises the documented same-inbox q @ [msg] cliff, since no cell receives more than one message; a fan-in/aggregator workload or nonzero sink assertion is needed before using this probe to justify deferring the queue refactor.
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Follow-up #1 to the DBSP consumer (#9129): measure the deferred O(n²)-queue hot path instead of assuming it.
What
A scale probe exercising the adversarial cases (wide fan-out, deep chain). Correctness-at-scale assertions are deterministic; wall-clock is informational only (not a DST proof).
Measured (N=2000)
Well within the design's stated "thousands of cells" target. The quadratic is real (fan-out ≈ O(N²) ⇒ ≈1.5s at N=10k) but does not bite at the target scale.
Outcome
The
ImmutableQueue+Set-membership refactor stays deferred — now with data, not a guess. The measurement says it isn't yet earned; earn it when a consumer targets ~5–10k cells. Debt ledger §6a updated with the numbers.This is the razor-honest disposition: measure first, refactor only when the number justifies it. It also proves the scheduler is correct at 2000 cells (nothing else exercised it beyond ~12).
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