1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
// SPDX-License-Identifier: AGPL-3.0-only
//! **Per-figure-of-merit validation tier.**
//!
//! Every number a study report shows next to a [`crate::fom::FoMScores`] field
//! is either externally *validated* against an authoritative oracle or it is a
//! *modelled* first-principles figure. A reader — especially a procurement
//! reviewer — must be able to tell which, inline, next to the value. This module
//! is the single name→tier lookup that surfaces that distinction.
//!
//! **Single source of truth.** The tier is *derived from* the existing
//! verification matrix ([`crate::verification::verification_matrix`]); this
//! module deliberately does **not** keep a second, independent matrix that could
//! drift. Each FoM field name is mapped to the matrix `requirement` that owns it,
//! and the tier is read back from that row's [`VerificationStatus`]. If a metric
//! has no owning row, the lookup returns the most conservative honest tier rather
//! than inventing a validation halo.
//!
//! **Why the timing FoMs are MODELLED.** The timing-domain figures
//! (`timing_rms_ns`, `timing_p95_ns`, `holdover_s`, `resilience_slope_ns_per_s`,
//! `availability`) are all produced by the clock-holdover scoring engine over a
//! *modelled* GNSS-denied coast (the matrix's "GNSS-denied clock holdover" /
//! "Onboard clock state estimation" rows, both `Modelled`). The `integrity` and
//! `security` FoMs are, per their own field docs in [`crate::fom::FoMScores`], a
//! Kalman self-consistency fraction and an analytic spoof-detectability bound —
//! explicitly **not** the externally-validated aviation RAIM / multi-satellite
//! detector. So they are mapped to their honest modelled rows, never to the
//! Validated RAIM core.
use crate::verification::{verification_matrix, VerificationStatus};
/// The honest validation tier shown next to a figure of merit in a report.
///
/// Mirrors [`VerificationStatus`] but in the FoM-reporting vocabulary the rest of
/// the product uses (`Partial` is reserved for a metric that is only validated in
/// part of its operating envelope; the current FoMs are all `Modelled`).
#[derive(Clone, Copy, Debug, PartialEq, Eq, serde::Serialize)]
pub enum ValidationTier {
/// Checked against an independent external oracle (dataset / published vectors
/// / published value) — see the matrix's `Validated` rows.
Validated,
/// Implemented from published or first-principles physics with tests, but not
/// checked against an external oracle to a stated tolerance.
Modelled,
/// Validated only over part of its operating envelope; modelled elsewhere.
Partial,
}
impl ValidationTier {
/// Short upper-case tag for inline rendering, e.g. `(MODELLED)`.
pub fn tag(self) -> &'static str {
match self {
ValidationTier::Validated => "VALIDATED",
ValidationTier::Modelled => "MODELLED",
ValidationTier::Partial => "PARTIAL",
}
}
}
/// The verification-matrix `requirement` that owns each FoM field. The tier is
/// read back from that row, so the matrix stays the single source of truth and
/// this is only a name→row crosswalk, never a second status table.
///
/// The timing-domain FoMs are owned by the modelled clock-holdover rows; the
/// `integrity`/`security` FoMs are mapped to the rows describing the actual
/// quantity reported (a filter self-consistency fraction; an analytic
/// spoof-detectability bound) — deliberately not the Validated aviation RAIM row,
/// because [`crate::fom::FoMScores`] documents those fields as *not* being it.
fn owning_requirement(fom: &str) -> Option<&'static str> {
Some(match fom {
"timing_rms_ns"
| "timing_p95_ns"
| "holdover_s"
| "resilience_slope_ns_per_s"
| "availability" => "GNSS-denied clock holdover",
"integrity" => "Onboard clock state estimation",
"security" => "Spoofing detection",
_ => return None,
})
}
/// The honest validation tier for a [`crate::fom::FoMScores`] field name, derived
/// from the verification matrix.
///
/// Returns `None` only for a name that is not a known FoM field. For a known FoM
/// whose owning row is missing from the matrix, returns the most conservative
/// honest tier ([`ValidationTier::Modelled`]) — it never fabricates `Validated`.
pub fn tier_for(fom: &str) -> Option<ValidationTier> {
let requirement = owning_requirement(fom)?;
let status = verification_matrix()
.into_iter()
.find(|it| it.requirement == requirement)
.map(|it| it.status);
Some(match status {
Some(VerificationStatus::Validated) => ValidationTier::Validated,
// A modelled, partner-owned, or (defensively) absent row all map to the
// conservative tier — never a validation halo the matrix didn't grant.
Some(VerificationStatus::Modelled) | Some(VerificationStatus::PartnerOwned) | None => {
ValidationTier::Modelled
}
})
}
#[cfg(test)]
mod tests {
use super::*;
// Every FoM field resolves to a tier; an unknown name does not.
#[test]
fn known_foms_resolve_unknown_does_not() {
for name in [
"timing_rms_ns",
"timing_p95_ns",
"holdover_s",
"resilience_slope_ns_per_s",
"availability",
"integrity",
"security",
] {
assert!(tier_for(name).is_some(), "no tier for {name}");
}
assert_eq!(tier_for("not_a_fom"), None);
}
// The tier is the matrix's status, not an independent assertion: every FoM's
// owning requirement must exist in the matrix and its tier must match.
#[test]
fn tier_is_read_back_from_the_matrix() {
let matrix = verification_matrix();
for name in [
"timing_rms_ns",
"timing_p95_ns",
"holdover_s",
"resilience_slope_ns_per_s",
"availability",
"integrity",
"security",
] {
let req = owning_requirement(name).expect("known FoM has an owning requirement");
let row = matrix
.iter()
.find(|it| it.requirement == req)
.unwrap_or_else(|| panic!("owning requirement '{req}' missing from matrix"));
let expected = match row.status {
VerificationStatus::Validated => ValidationTier::Validated,
_ => ValidationTier::Modelled,
};
assert_eq!(tier_for(name), Some(expected), "tier drift for {name}");
}
}
// The honest expectation: holdover is a modelled coast, never validated.
#[test]
fn holdover_is_modelled() {
assert_eq!(tier_for("holdover_s"), Some(ValidationTier::Modelled));
}
// The tag strings are stable for inline rendering.
#[test]
fn tags_are_stable() {
assert_eq!(ValidationTier::Validated.tag(), "VALIDATED");
assert_eq!(ValidationTier::Modelled.tag(), "MODELLED");
assert_eq!(ValidationTier::Partial.tag(), "PARTIAL");
}
}