docs(docs): root-cause and record the phantom pad in a dual remap#11
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Two DualSense both in ps5-xbox make Steam list a fifth, inert PlayStation pad. Hardware verification shows the hidraw gate holds on both pads (both nodes 000, no holder); the leak is the second pad's evdev node, re-opened by Steam during the second transition's driver rebind. EVIOCGRAB keeps it input-dead, so it is cosmetic, not double input. No lightweight robust fix exists: the daemon is a --user service sharing Steam's UID, so an evdev permission/ACL barrier that blocks Steam also locks out the remapper's own grab. Decision: document and defer; escalate to a root fd-passing grab (born-gated evdev node + SCM_RIGHTS) only if a game-side slot test shows functional harm (stolen player slot). - docs/decisions/evdev-enumeration-leak.md: full analysis and decision - docs/troubleshooting.md: symptom + inert-case verification - ROADMAP.md: status entry and known-limitation backlog item
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What
Documents the phantom fifth controller Steam lists when two DualSense are both in
ps5-xbox, and records the decision to defer the fix.Root cause (hardware-verified, 2026-07-15)
000, no holder) — hidraw is not the leak.the driver rebind of the second
ps5-xboxtransition.EVIOCGRABstill holds it, so it isinert —
evtestreports the node grabbed, no events leak, no double input.EVIOCGRABhides events, not enumeration; Steam reads the VID/PID off the evdev node andlists it regardless of the grab. Always the second pad, position- not device-specific.
Why deferred
The daemon is a
--userservice sharing Steam's UID, so any evdev permission/ACL barrier thatblocks Steam also locks out the remapper's own grab. The only robust fix (born-gated evdev node
SCM_RIGHTS+ a raw-read remapperpath) expands a security-sensitive privileged surface for a cosmetic list entry. Decision:
document and defer; escalate only if a pending game-side slot test shows functional harm.
Changes (docs only, no runtime change)
docs/decisions/evdev-enumeration-leak.md— full analysis, decision, rejected alternativesdocs/troubleshooting.md— symptom + inert-case verificationROADMAP.md— status entry and known-limitation backlog itemRepo validation (
scripts/validate-repo.sh) passes, including internal-link checks.