A P0 traceability audit per the project's compliance workflow
found exactly one gap across the 162 P0 SRS items:
* SRS-200 (mouse side buttons as bindable inputs for desktop
Global PTT) had no dedicated SAD item. The earlier baseline
matrix folded SRS-200 under the narrative
`SRS-195..203 -> SAD-071..079` umbrella, which technically
covered the requirement at the table level but did not give
SRS-200 a one-to-one SAD source the validator's strict
discipline expects.
Per the project's gate-check workflow (Case C —
BLOCKED_MISSING_SAD) this commit closes the documentation chain
*before* claiming compliance for the already-merged mouse-side-
button code path:
* `docs/architecture/sad.md` v0.9.4 — new `SAD-080` sources
SRS-200, allocates `Audio (Windows / macOS / Linux), Bridge,
Flutter UI`, and records the cross-platform mouse-side-button
surface as a software-architecture item. The §27 coverage
matrix gains a dedicated SRS-200 -> SAD-080 row.
* `docs/architecture/sdd.md` v0.9.4 — new `SDD-093` sources
SAD-080. Specifies the `PttInputClass` enum surface
(`None` / `Keyboard` / `MouseSideButton`), the rebind
contract on the Windows + macOS backends, the Linux portal's
pass-through behaviour, and the Flutter
`PointerEvent.buttons` bitmask capture (back = `0x08`,
forward = `0x10`). The §11 coverage matrix gains the
SAD-080 -> SDD-093 row.
* `docs/governance/traceability-matrix.md` v0.9.4 — the
`(DEC-026 mouse buttons)` row moves from
`SAD-072..074 / SDD-082..086` to the dedicated
`SAD-080 / SDD-093`.
* `docs/governance/baseline-candidate-validation-report.md`
v0.9.4 — ID totals advance to 302 / 148 / 203 / 80 / 93;
direct-layer-rule and undefined-reference counts remain
zero.
* `docs/governance/repo-format-validation-report.md` v0.9.4 —
same ID totals update.
Audit summary
-------------
* 162 P0 SRS items audited.
* 1 SAD-coverage gap (SRS-200) — closed by this commit.
* 0 SDD-coverage gaps (every PTT SAD has explicit SDD coverage;
the inherited baseline `SAD-032/033` are covered through the
documented range row, not individually).
* All Priority: P0 software requirements now have a strict
SRS -> SAD -> SDD chain on file.
Validator output:
```
[OK] SysRS: 302 defined, 0 undefined references
[OK] SysDes: 148 defined, 0 undefined references
[OK] SRS: 203 defined, 0 undefined references
[OK] SAD: 80 defined, 0 undefined references
[OK] SDD: 93 defined, 0 undefined references
[OK] SRS direct SysRS references: 0
[OK] SAD direct SysRS references: 0
[OK] SAD direct SysDes references: 0
[OK] SDD direct SysRS references: 0
[OK] SDD direct SysDes references: 0
[OK] SDD direct SRS references: 0
```
Implementation status
---------------------
The mouse-side-button code was implemented in v1.0.0-rc.4 and
v1.0.0-rc.5 under the (then-implicit) PTT umbrella; the code
already matches the new SDD-093's contract verbatim. This
commit ships **documentation only** — it adds the SAD/SDD/matrix
rows that retroactively justify the existing implementation
under the strict traceability discipline. No code edits, no test
edits.
* `cargo test --workspace`: 67/67 green (unchanged).
* `cargo deny check`: advisories ok, bans ok, licenses ok,
sources ok.
* `cargo about generate`: zero new warnings (no Cargo.lock
delta).
* `flutter analyze`: clean.
* `tools/validate_docs.py`: all SRS/SAD/SDD coverage and
direct-layer-rule checks pass.
Outstanding open items remain live verification per
`docs/release/release-readiness-go-nogo-record.md`
(RR-PTT-001..006/008) and the DEC-012 legal review; both are
non-engineering work.