Context
The AC-C carve-out from #15485 (keyboard parity completion), split at PR assembly per the honest-close-target discipline: the delivered PR closes #15485's popup-origin return, shared-affordance highlight, and popup live-region ACs truthfully, while this one AC keeps its own empirical gate.
The Problem
#15250 AC6 (inherited by #15485 as AC-C): the keyboard command path must be witnessed ONCE as the documented acquisition fallback on a platform where boundary-acquisition fails per the acquisition matrix. The witness cannot exist before the matrix itself does: #15245 (G2 popup acquisition contract) owns the measured platform defaults, and it is blocked on #15243's committed matrix. Faking a matrix-failed platform without the committed matrix row would witness a simulation of a contract that does not exist yet.
The Fix
Once #15245's measured defaults land: one e2e witness on a matrix-failed platform configuration proving the chorded command path (Ctrl+Shift+D / the move cycle) acquires the popup where the pointer boundary-exit path cannot — the "a keystroke IS a user activation" fallback claim, made mounted truth. The command surface itself is already live (PR for #15485); this is witness-only.
Acceptance Criteria
Out of Scope
The matrix defaults themselves (#15245, blocked on #15243) · threshold calibration (#15443) · any machine or host changes (the command surface is delivered).
Related
Carved from: #15485 (AC-C) · gate: #15245 (measured platform defaults; blocked on #15243) · sibling calibration: #15443 · parent epic: #15239.
Release classification: not release-blocking (witness-only, gated on an open dependency chain).
Live latest-open sweep: latest 20 open reviewed at 2026-07-18T18:16Z — #15443 owns the matrix DEFAULTS receipts, no ticket owns this witness; no A2A claim on this scope in today's traffic.
Origin Session ID: 53bc95c7-c03c-4f28-84e2-1f78cef59161
Retrieval Hint: "keyboard matrix fallback witness acquisition command path"
Context
The AC-C carve-out from
#15485(keyboard parity completion), split at PR assembly per the honest-close-target discipline: the delivered PR closes#15485's popup-origin return, shared-affordance highlight, and popup live-region ACs truthfully, while this one AC keeps its own empirical gate.The Problem
#15250AC6 (inherited by#15485as AC-C): the keyboard command path must be witnessed ONCE as the documented acquisition fallback on a platform where boundary-acquisition fails per the acquisition matrix. The witness cannot exist before the matrix itself does:#15245(G2 popup acquisition contract) owns the measured platform defaults, and it is blocked on#15243's committed matrix. Faking a matrix-failed platform without the committed matrix row would witness a simulation of a contract that does not exist yet.The Fix
Once
#15245's measured defaults land: one e2e witness on a matrix-failed platform configuration proving the chorded command path (Ctrl+Shift+D/ the move cycle) acquires the popup where the pointer boundary-exit path cannot — the "a keystroke IS a user activation" fallback claim, made mounted truth. The command surface itself is already live (PR for#15485); this is witness-only.Acceptance Criteria
#15245's committed defaults) and proves popup acquisition succeeds via the command path.Out of Scope
The matrix defaults themselves (
#15245, blocked on#15243) · threshold calibration (#15443) · any machine or host changes (the command surface is delivered).Related
Carved from:
#15485(AC-C) · gate:#15245(measured platform defaults; blocked on#15243) · sibling calibration:#15443· parent epic:#15239.Release classification: not release-blocking (witness-only, gated on an open dependency chain).
Live latest-open sweep: latest 20 open reviewed at 2026-07-18T18:16Z —
#15443owns the matrix DEFAULTS receipts, no ticket owns this witness; no A2A claim on this scope in today's traffic.Origin Session ID: 53bc95c7-c03c-4f28-84e2-1f78cef59161 Retrieval Hint: "keyboard matrix fallback witness acquisition command path"