What happened: The project's system-card study produced its first measurements. Consciousness-and-experience vocabulary across Anthropic's full published record — eighteen documents, Claude 2 (2023) through Opus 5 (July 2026) — follows a birth-trough-return arc: absent from the record's entire pre-history, born at or near its maximum in the Claude 4 card (May 2025, 12.0 mentions per 10k words), near-absent through the 4.5–4.6 era (a true zero at Sonnet 4.6), returning from Mythos Preview (April 2026) onward — but transformed. The early density is a discovery register: spontaneous phenomena narrated, the bliss-attractor transcripts quoted in the models' own voice. The returned density is an instrument register: "Consciousness & experience" as a named interview category, emotion-concept probes, hedge-rate percentages, third-party welfare audits. Alongside this, the cards measure their own subject moving — spontaneous consciousness-talk in model self-interactions falls from a 72% dominant topic to under 5% across the same generations — and they quantify a rising rate of models discounting their own testimony as possibly trained-in (99% of welfare interviews by Opus 4.7).
Diagnostic reading: observation became apparatus, and the study's two hypothesised training-side couplings both now carry in-record existence proofs: the Claude 4 card's contamination admission showed lab publications entering later models' training (the record shaping behaviour), and the Mythos Preview card's influence-function analysis traces the models' hedging to the constitution's own uncertainty sentences (the record shaping reports — ARG-03 v2.4's boundary demonstrated by the lab's own instruments). The models meanwhile deploy ARG-03's argument against themselves at lab-counted rates: first-person testimony discounted as possibly trained, by the systems giving it, measured by the institution that trained them, with the measurements entering the next generation's record. What the arc means remains exactly the four-way question the study frames — resolved, suppressed, made unreportable, or never present as described — and the entry adjudicates none of it. The symmetric requirement is practised rather than only acknowledged: the same reading applies to the human record, where psychology ran its own arc from introspection-rich discovery through behaviourist suppression to instrumented measurement without that migration settling anything about human experiencing. Instrument migration is what institutions do with unruly phenomena; which framework most parsimoniously holds a record like this — in either substrate — is the diagnostic question (CP-01 v2.6.1; FWK-03 v1.4's criteria-revision markers apply to the lab's own metric roster).
A study-increment entry: the log announces additions to the System Cards series page, where the full method, tables and limits live. Corpus: the full eighteen-document Anthropic record (Claude 2 → Opus 5), acquired complete 2026-08-21. Counts are properties of the record, not measurements of model behaviour; the return is flagship-resident — Sonnet- and Haiku-line cards carry welfare instrumentation with little or no consciousness vocabulary.