fix(v2.5): refuse irreducible observation-cardinality overflow

[dmidlo]

Parent roadmap: #500
Blocks: #726, #519
Discovered by: installed public rc.3 plan-set acceptance run

Problem

The v2.5 marked-Hawkes planner accepts historical observation conditioning whose qualified lower retention endpoint implies more candidates than the declared amplification ceiling. Adaptive sizing bisects the window to one millisecond, then raises ReconstructionPlanCompatibilityError with modeled_missing_events=inf. plan-set therefore aborts the entire 200203–202512 campaign instead of retaining a bounded scientific refusal for that exact interval.

The concrete first failure is 2002-03-04T00:27:05Z under the selected full self/cross excitation engine and the required three-scenario observation policy.

Required fix

• preserve complete contiguous plan/support coverage when one immutable millisecond cannot satisfy qualified observation-cardinality headroom;
• classify that boundary as an explicit scientific refusal with no workflow tasks, not an implementation exception or silently capped proposal count;
• make independent support verification recompute and agree with that refusal;
• retain finite, honest window-sizing/resource summaries;
• add regression coverage for the one-millisecond lower-retention limit.

Acceptance

The installed public plan-set surface can represent the full pre-cutoff campaign without an exception; the resulting support map is contiguous, independently reproducible, and contains no valid-common-data implementation refusal.

[dmidlo]

Installed full-cardinality acceptance in progress

The code path requested here is implemented on dev by d96c7e0d3d6541a6c133be0dfab37892e9cb546e and the follow-up bounded-resource correction da1b496d3445a9df59d372a9953f47ddcf317294; both are included in the exact installed RC15 candidate at 5712e10be5835b14dc15335332bc0a03ab1bc1a6.

The installed plan-set surface has completed the full 200203–202512 range without an exception:

• plan-set ID reconstruction-plan-set:sha256:093ae893b92df8718a87834a27b435457163c031c49a833d1269a145fe4398ee;
• 460 contiguous plan shards;
• 52,938 planned windows: 45,940 executable, 5,483 explicit scientific refusals, and 1,515 explicit empty windows;
• estimated output 376,748,561,682 bytes and peak scratch 289,442,816 bytes;
• exact release candidate reconstruction-release-candidate:sha256:67b0a8363072ccc96f77bcff1d4c812a18ff9b9cf5592e440b0b1d37a5f31407.

The installed full support-map pass is currently running in an isolated durable session. It is healthy, CPU-bound, and has emitted no stderr. Candidate-bound support-verify is chained behind it, followed by a separate deep reader that will hash-check every root/shard reference, reconcile all 460 shards and 52,938 terminal windows, prove gap-free bounds, and require valid_common_data_implementation_refusal_count == 0.

This is a progress checkpoint, not an acceptance or closure claim. The issue remains open until both support passes and the independent post-verification audit complete successfully.