M3/E5/#17 — SoLEXS parsers

[Rexy-5097]

Canonical identifier: Milestone M3 · Epic E5 · Issue #17 — SoLEXS parsers
Dependencies: #12 ✔, #15 ✔
Selection: eligibility from origin/main:docs/tis/TIS-v1.0.md §15 — complete {1…16}, eligible {#17, #22, #23, #25, #26, #27, #39}; lowest Order selects #17.

Three parsers, one per SoLEXS product, each implementing its section of SPEC-parsers@r6 — a document that is a contract: "a deviation requires a logged amendment, not a code change."

lc    §2.1   total-band counts per second. NaN is data, not an error.
pi    §2.2   340-channel PI spectra per second. Ordinal channels; keV is prohibited.
gti   §2.3   inclusive second-marks; Σ(STOP−START+1) == EXPOSURE, exactly.

No default on a missing key — the rule the spec opens with

§5: "No default-on-missing-key (header.get(K, default) is banned for any physically meaningful key — that idiom is the direct cause of v1's thirty-sprint failure)."

The concrete failure was F-05: v1 defaulted MJDREF to 58484 where the archive declares 40587 — a ~49-year timestamp error that nothing detected. So _fits.py has no get. Every lookup raises. Five tests delete a keyword and require the parse to abort.

NaN is data. Zero is a measurement. They never meet.

§2.1 as amended at r2, binding: NaN is the missing-data sentinel; NaN values pass through unchanged, are never imputed, never converted to zero, never removed; zero remains a valid physical count.

Mapped onto the domain exactly: NaN → None (observed to be absent, ADR-0017/L-07), 0.0 → 0.0. The property is quantified over every position and in both directions, because collapsing the two is the one error that would be undetectable in every downstream artifact. No interpolate/smooth/fill/impute/resample/repair exists in any of the three modules, and a test asserts none appears.

F-19 is checked after the NaN branch, which is what makes §2.1's note true that the rule is "inherently NaN-safe (NaN < 0 is False)".

The keV prohibition, enforced by absence

§2.2: no RMF/ARF exists anywhere in the archive, so PI-channel → keV is impossible from archive contents alone, and "no v2 artifact may state a SoLEXS energy in keV until a response file is acquired."

There is no keV field, no conversion function and no calibration constant — a test scans the module and its three classes for any of them. A comment is not a constraint; an absent field is.

Exact means exact

F-09 requires Σ(STOP−START+1) == EXPOSURE with tolerance 0 s. §5 says why: "the relation is definitional, and a tolerance would re-admit the ambiguity that produced CONTRADICTION-001." A one-second discrepancy — precisely what the superseded exclusive reading produces — aborts. The convention is verified for 2024-05-14 SDD2 only (§8 A-8) and is not widened here.

Verified against the real archive — every OBSERVED value reproduced

Re-measured from the 2024-05-14 SDD2 products, the X8.7 flare day:

Measured	Spec clause
86,400 rows	§2.1 NAXIS2
5 NaN at offsets [0, 5, 30072, 30078, 83951]	§2.1 OBSERVED, exactly
86,395 finite	§2.1, == EXPOSURE
5 GTI intervals, Σ(STOP−START+1) = 86395.0	§2.3, zero error
GTI-excluded set == NaN set	§2.1 OBSERVED, this day
SDD1 NAXIS2 = 0 → detector_active=False	F-12, the one non-fatal rule
TSTART 1715644800.0 = 2024-05-14T00:00:00Z	§2.1 epoch anchor
DETCHANS 340, CHANTYPE PI, map 0..339	§2.2
.pi TSTART[0] == .lc TSTART	V-PI-3 / F-06

These are the specification's own OBSERVED claims, independently reproduced by this code. A drift in either the parser or the archive is now a red test rather than a quiet disagreement between a document and reality.

astropy granted to Ingest — the line #13 predicted

Reading FITS needs a FITS reader. M2/E4/#13 declined to pre-grant third-party roots and said why: "a context that later needs astropy should add one reviewable line rather than inherit a blanket permission nobody voted for (STD-11)."

Three existing tests pinned contexts.ingest.allow == {contracts, domain, kernel} and went red — the mechanism working. They are updated to be stricter, not looser: internal grants must still equal ADR-0026's exactly, and a new test enumerates every third-party grant and refuses any that names a governed root of this repository.

Scope

.hk (§2.4, v1.1 only, 5 of 436 days) is not implemented: TIS E5 §5 lists this epic's SoLEXS modules as parsers/solexs/{lc,pi,gti} and assigns no .hk module to any issue. Reported as an Engineering Plan Defect rather than filled by guessing at scope.

No aggregation to the 1-minute grid — §3's T1/T2 contract is the write path's (#19). No NaN ⇒ GTI-excluded evaluation — §2.1 places it at the day-assembly layer explicitly, "not inside the single-file .lc parser." No HEL1OS, no curation, no registry.

Verification

unit (kernel + domain + contexts)  470 passed   (+65)
tests/architecture                 563 passed   (+1)
tests/integration                  128 passed   (+14)
research/tests/v2                  188 passed
links / imports / contracts gates  clean
imports gate: 46 modules, 211 imports, 9 policies

clean export (git archive HEAD, archive absent):
  unit 468 passed, 2 skipped · integration 94 passed, 10 skipped
  → all 12 real-corpus tests SKIP, never fail: E5 §17 satisfied

CI impact

numpy + astropy added to the unit and integration jobs — without them the parser suites would error at import rather than run. No new job, no new required context; still eight.

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