feat(host,web): experimental DDC/CI monitor power-off for Exclusive sessions

The sole-virtual-display stutter investigation's active experiment: when the Exclusive isolate deactivates a physical monitor, the dark-but-connected head keeps getting serviced (monitor standby auto-input-scan / DP link churn) at a seconds-scale cadence — the leading suspect for the periodic double-jolt. A panel commanded off over DDC/CI (the VESA monitor-control channel in the video cable) believes it has an owner and, on cooperating firmware, stops probing. - New `ddc_power_off` display-policy axis (default off): orthogonal to presets like game_session, stored in display-settings.json, surfaced in GET/PUT /display/settings + the enforced list, carried through the layout transform. - windows/ddc.rs: VCP 0xD6 power-mode control via the dxva2 Physical Monitor API. Deliberately DPMS-off (0x04, DDC stays responsive, signal return wakes) and never power-button-off (0x05, bricks-until-button on many monitors). Probe-before-write; every failure is skip-and-log — monitors without DDC/CI, OSD-disabled, or behind docks/KVMs degrade to a logged no-op. - Manager wiring: panels commanded off immediately BEFORE the Exclusive CCD isolate (an HMONITOR — and with it the DDC channel — only exists while the display is active); teardown wakes them right after the CCD restore, where returning signal alone already wakes most firmware. - Web console: an Experimental-badged on/off control on the display card, applied immediately like the game-session axis and preserved across preset switches; EN/DE strings incl. the wake-failure escape hatch (press the monitor's power button once, turn the option off). Diagnostic value on top of the fix: if this kills a reporter's stutter, the churn is monitor-firmware-initiated; if only topology=primary/extend does, the driver services dark heads regardless — the two remaining root-cause classes. Verified: Linux 258 tests + clippy + fmt clean; Windows (RTX box) 220/220 + clippy clean; web tsc + production build clean; openapi.json regenerated. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-10 12:32:36 +02:00
parent f68f6bc590
commit cca5008805
9 changed files with 322 additions and 8 deletions
@@ -2517,6 +2517,10 @@
        "type": "object",
        "description": "The user-facing display-management policy — what `display-settings.json` holds and what the mgmt\nAPI GETs/PUTs. When [`preset`](Self::preset) is not [`Preset::Custom`] the explicit fields are\nignored (the console writes one or the other); [`effective`](Self::effective) resolves both to a\nsingle [`EffectivePolicy`].",
        "properties": {
+          "ddc_power_off": {
+            "type": "boolean",
+            "description": "EXPERIMENTAL (Windows): command physical monitors' panels off over DDC/CI (VCP 0xD6 →\nDPMS off) right before an `Exclusive` isolate deactivates them, and back on at restore.\nTargets the \"connected-but-dark head\" periodic-stutter class (monitor standby\nauto-input-scan / DP link churn while the virtual display is the sole active display) at\nthe monitor-firmware level. Best-effort — monitors without DDC/CI (or with it disabled in\nthe OSD) are skipped. Orthogonal to `preset` (like `game_session`): preserved across\npreset changes; `#[serde(default)]` = off so existing `display-settings.json` files are\nuntouched."
+          },
          "game_session": {
            "$ref": "#/components/schemas/GameSession",
            "description": "How a game-launching session is served (`design/gamemode-and-dedicated-sessions.md` §5.2).\nOrthogonal to `preset`/lifecycle — preserved across preset changes; `#[serde(default)]` = `Auto`\nso existing `display-settings.json` files are untouched."