feat(psychometric): recover Driver p.16 discreteCINTstd after positive p

[seonghobae]

Stacked on #212 (asymDIFFUSIONstd). Next unique licensed map on this ancestry is footnote-4 standardisation of 2017-era discreteCINT. Do not duplicate #203 addedTIPREDVARstd. TDPREDVARstd is commented out in the 2017-era source and is not recovered. CINTstd (#195) is not on this ancestry; κ/√p is computed inline and is not this map.

Driver, Oud, and Voelkle (2017, p. 16; Eq. 3, p. 4; footnote 4; Table 2, p. 12; JSS PDF re-opened 2026-08-24T05:20Z) print discrete-time transformations for a chosen event interval and, when appropriate, standardised matrices with the suffix std. Footnote 4 standardises using only the relevant variance. CINT is the process intercept of individual, or average individual, dynamics, so that relevant variance is within-subject asymDIFFUSION p = −q / (2 a). The 2017-era summary.ctsemFit.R forms discreteCINT whenever verbose = TRUE:

discreteCINT <- solve(DRIFT) %*% (discreteDRIFT - I) %*% CINT

That source does not form a discreteCINTstd matrix. The scalar map here is the footnote 4 standardisation of that named discrete intercept: A^{-1}[e^{A Δt} − I] κ / √p.

Recovery

• recover_standardised_discrete_continuous_intercept(κ, q, a, Δt, clock) forms strictly positive p first, then the discrete intercept, then divides by √p.
• A zero intercept is exactly zero.
• A later event interval changes the result.
• Zero q fails closed. Unstandardised discreteCINT is defined for growing a ≥ 0 and for zero diffusion; standardised discreteCINT is not.
• Non-event clock fails closed.
• Non-positive event interval fails closed.
• a ≥ 0 fails closed (lasting asymDIFFUSION requires stable drift).

Claim boundary

• Unstandardised discreteCINT is not discreteCINTstd.
• κ / √p does not depend on Δt and is not this finite-interval map.
• (−κ / a) / √p is the standardised asymptotic intercept and is not this map.

Meredith (1993) and Mislevy (1991) remain closed (Unpaywall 2026-08-24T08:02Z: is_oa: false, 0 locations).

Do not merge without an independent APPROVE plus exact-head required-check success. Do not self-approve. Do not request Copilot.

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[seonghobae]

Maintainer Verification — exact head d32c069b0bcf35acda15c7bd59e18327ef5e8171\n\n- Scope: recover Driver p. 16 discreteCINTstd from strictly positive stationary within-subject variance, with documentation corrected to preserve valid signed intercepts and a direct expm1 scientific oracle plus negative-effect regression.\n- Verification: focused contract (2/2), workspace check, workspace tests, doc tests, clippy -D warnings, cargo-deny, format — PASS on Rust 1.97.1.\n- Hosted state: this push dispatched new exact-head checks; pending is not treated as success.\n- Review state: PR remains Draft and has no qualifying independent approval.\n- Decision: WAIT_AND_REMEDIATE; re-evaluate after exact-head Checks and substantive review.