feat(cli): publish desktop audio exclusion

README.md

@@ -21,7 +21,8 @@ Working:
 - VAAPI H.264 encode in GStreamer (RDNA3 confirmed; other VAAPI-capable
   GPUs should work), with a software x264 fallback via `--no-hwencode`
 - Audio capture of the default sink's monitor, with optional per-app
-  routing (`--app <name>`)
+  routing (`--app <name>`) and a guarded whole-desktop mode for parent
+  integrations (`--audio-mode=desktop-excluding`)
 - `--repair` cleanup of orphaned PipeWire state left by a crashed host
 - `--doctor` environment diagnostic (capture/encode deps, VA-API H.264,
   viewer player, relay reachability) — see [Diagnostics](#diagnostics)
@@ -316,12 +317,34 @@ matches a built-in overrides that built-in.
 ## Audio
 
 By default pixelpass captures the default sink's monitor — the viewer
-hears whatever the host hears. `--app <name>` narrows that to a single
-application: pixelpass creates a per-PID null-sink and uses libpipewire to
-reroute matching `Stream/Output/Audio` nodes (by `application.name`) into
-it, so the viewer hears just that app instead of the whole desktop. In the
-interactive menu you can pick the app from a list of what's currently
-playing.
+hears whatever the host hears. This is also available explicitly as
+`--audio-mode=desktop-shared`.
+
+`--app <name>` narrows capture to a single application: pixelpass creates a
+per-PID null-sink and uses libpipewire to reroute matching
+`Stream/Output/Audio` nodes (by `application.name`) into it, so the viewer
+hears just that app instead of the whole desktop. In the interactive menu
+you can pick the app from a list of what's currently playing.
+
+Parent integrations can select guarded whole-desktop capture with
+`--audio-mode=desktop-excluding`. This copies eligible playback streams into
+a connection-owned capture sink while excluding PeerSpeak-tagged playback,
+the exact configured echo-canceller, unsafe ancestry, and unsupported stream
+formats. The mode requires an explicit AEC state so a missing integration
+argument cannot silently mean "no AEC":
+
+```sh
+pixelpass --host --audio-mode=desktop-excluding --aec=off
+pixelpass --host --audio-mode=desktop-excluding --aec=pulse-module:536870919
+```
+
+Integrations should use `pixelpass --capabilities`, not scrape `--help`. Its
+versioned response advertises strict per-app audio and desktop exclusion as
+independent capabilities:
+
+```json
+{"schema_version":1,"capabilities":{"strict_app_audio":true,"desktop_audio_exclusion":true}}
+```
 
 Microphone capture is intentionally out of scope — pixelpass is a
 screen-share tool meant to be paired with a dedicated voice app (Mumble,
@@ -407,9 +430,10 @@ each take precedence over the chosen preset's value for that field.
   either one breaks playback (the first kills the demuxer, the second
   kills the H.264 decoder). pixelpass warns at player-launch time if
   either plugin isn't on disk. mpv doesn't share these dependencies.
-- **Audio echo** if the host plays the stream through speakers and
-  captures system audio — expected, the mic / monitor picks up the
-  playback. Headphones bypass it.
+- **Audio echo in `desktop-shared` mode** if the host plays the stream through
+  speakers while capturing system audio. The guarded `desktop-excluding`
+  mode requires a cooperating parent integration to tag its playback and
+  supply the active AEC identity.
 - **Late joiners see ~2 s of garbage** before the next keyframe lets
   their decoder lock. Expected behavior, not a bug.
 - **VAAPI driver must be package-tracked**, not an orphaned `.so` on

src/capabilities.rs

@@ -0,0 +1,59 @@
+//! Versioned machine-readable feature discovery for parent integrations.
+//!
+//! PeerSpeak may execute an older PixelPass from `PATH`, so recognizing a CLI
+//! token in `--help` cannot be the primary protocol. This response advertises
+//! strict per-app audio and desktop audio exclusion independently; neither can
+//! accidentally imply the other.
+
+use anyhow::{Context, Result};
+use serde::Serialize;
+use std::io::Write;
+
+const CAPABILITY_SCHEMA_VERSION: u32 = 1;
+
+#[derive(Serialize)]
+struct CapabilityResponse {
+    schema_version: u32,
+    capabilities: CapabilitySet,
+}
+
+#[derive(Serialize)]
+struct CapabilitySet {
+    strict_app_audio: bool,
+    desktop_audio_exclusion: bool,
+}
+
+fn response() -> CapabilityResponse {
+    CapabilityResponse {
+        schema_version: CAPABILITY_SCHEMA_VERSION,
+        capabilities: CapabilitySet {
+            strict_app_audio: true,
+            desktop_audio_exclusion: true,
+        },
+    }
+}
+
+fn write_response(mut writer: impl Write) -> Result<()> {
+    serde_json::to_writer(&mut writer, &response()).context("serialize capability response")?;
+    writeln!(writer).context("write capability response")
+}
+
+pub fn run() -> Result<()> {
+    write_response(std::io::stdout().lock())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn version_one_wire_shape_is_exact_and_capabilities_are_independent() {
+        let mut output = Vec::new();
+        write_response(&mut output).expect("serialize the capability golden");
+        assert_eq!(
+            output,
+            br#"{"schema_version":1,"capabilities":{"strict_app_audio":true,"desktop_audio_exclusion":true}}
+"#
+        );
+    }
+}

src/cli.rs

@@ -1,6 +1,8 @@
 use anyhow::{Result, bail};
 use clap::{Parser, ValueEnum};
 
+use crate::host::aec::{AecConfig, parse_aec_arg};
+
 #[derive(Parser, Debug)]
 #[command(
     name = "pixelpass",
@@ -39,9 +41,36 @@ pub struct Cli {
     #[arg(long)]
     pub strict_audio: bool,
 
-    /// Internal phase-0d trigger for the not-yet-public desktop-excluding
-    /// capture plan. Phase 7 replaces this with the versioned public selector.
-    #[arg(long, hide = true, conflicts_with = "app")]
+    /// Select whole-desktop audio behavior. `desktop-shared` captures the
+    /// default output mix. `desktop-excluding` captures system audio while
+    /// excluding PeerSpeak-owned playback and the configured AEC identity.
+    #[arg(
+        long,
+        value_enum,
+        value_name = "MODE",
+        requires = "host",
+        conflicts_with_all = ["app", "internal_desktop_excluding"]
+    )]
+    pub audio_mode: Option<AudioModeArg>,
+
+    /// Echo-canceller identity for `--audio-mode=desktop-excluding`.
+    /// PeerSpeak passes `off` when no AEC is active, or the exact Pulse module
+    /// index returned by `pactl load-module` as `pulse-module:<idx>`.
+    #[arg(
+        long,
+        value_name = "off|pulse-module:<idx>",
+        requires = "host",
+        value_parser = parse_aec_cli
+    )]
+    pub aec: Option<AecConfig>,
+
+    /// Internal phase-0d trigger retained for deterministic compatibility and
+    /// mutation tests. Production integrations use `--audio-mode`.
+    #[arg(
+        long,
+        hide = true,
+        conflicts_with_all = ["app", "audio_mode"]
+    )]
     pub internal_desktop_excluding: bool,
 
     /// Override display server autodetection.
@@ -107,6 +136,10 @@ pub struct Cli {
     #[arg(long, short)]
     pub verbose: bool,
 
+    /// Print the versioned machine-readable capability response, then exit.
+    #[arg(long)]
+    pub capabilities: bool,
+
     /// Clean up orphaned PipeWire state from a crashed host run, then exit.
     #[arg(long)]
     pub repair: bool,
@@ -162,6 +195,14 @@ pub enum OutputFormat {
     Json,
 }
 
+/// Public values for the whole-desktop audio selector. These names are the
+/// Phase-7 cross-repository CLI contract consumed by PeerSpeak.
+#[derive(ValueEnum, Clone, Copy, Debug, PartialEq, Eq)]
+pub enum AudioModeArg {
+    DesktopShared,
+    DesktopExcluding,
+}
+
 /// Quality preset. Each fixed preset bundles a (max-height, bitrate, fps)
 /// tuple — resolution is a quality-per-bitrate knob, so the three only make
 /// sense together. `Auto` has no fixed tuple; it picks one of the others from
@@ -180,9 +221,8 @@ pub enum Quality {
     Auto,
 }
 
-/// Internal input to the typed audio-capture planner. `DesktopExcluding` is
-/// deliberately reachable only through a hidden phase-0d trigger until the
-/// public selector and capability contract land in phase 7.
+/// Internal input to the typed audio-capture planner. The public `AudioModeArg`
+/// is resolved to this type once, at the CLI boundary.
 #[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
 pub(crate) enum CaptureMode {
     #[default]
@@ -197,12 +237,12 @@ impl CaptureMode {
         }
         if app.is_some() {
             bail!(
-                "the internal desktop-excluding mode conflicts with --app; refusing to fall back to legacy per-app routing"
+                "desktop-excluding audio conflicts with --app; refusing to fall back to legacy per-app routing"
             );
         }
         if legacy_null_sink {
             bail!(
-                "the internal desktop-excluding mode conflicts with PIXELPASS_AUDIO_VIA_NULL_SINK; refusing to load the legacy default-monitor loopback"
+                "desktop-excluding audio conflicts with PIXELPASS_AUDIO_VIA_NULL_SINK; refusing to load the legacy default-monitor loopback"
             );
         }
         Ok(())
@@ -229,9 +269,12 @@ pub struct HostOpts {
     pub no_hwencode: bool,
     pub max_viewers: Option<u32>,
     pub interactive: bool,
-    /// Phase-0d internal selector. This is not a public capability or protocol
-    /// surface; phase 7 owns that promotion.
+    /// Resolved public or test-only selector.
     pub(crate) capture_mode: CaptureMode,
+    /// Explicit AEC state for desktop-excluding fan-out. Legacy invocations
+    /// resolve to `Off`; public desktop-excluding invocations must spell this
+    /// on argv so absence can never masquerade as "no AEC".
+    pub(crate) aec: AecConfig,
     /// Snapshot the legacy dogfood override during CLI resolution. Capture is
     /// lazy, so reading the process environment later would let it change modes
     /// between ticket creation and the first viewer.
@@ -259,12 +302,25 @@ impl Cli {
         interactive: bool,
         legacy_null_sink: bool,
     ) -> Result<HostOpts> {
-        let capture_mode = if self.internal_desktop_excluding {
-            CaptureMode::DesktopExcluding
-        } else {
-            CaptureMode::Legacy
+        let public_desktop_excluding = self.audio_mode == Some(AudioModeArg::DesktopExcluding);
+        let capture_mode = match self.audio_mode {
+            Some(AudioModeArg::DesktopExcluding) => CaptureMode::DesktopExcluding,
+            Some(AudioModeArg::DesktopShared) => CaptureMode::Legacy,
+            None if self.internal_desktop_excluding => CaptureMode::DesktopExcluding,
+            None => CaptureMode::Legacy,
         };
         capture_mode.validate_inputs(self.app.as_deref(), legacy_null_sink)?;
+        let aec = match (capture_mode, self.aec) {
+            (CaptureMode::DesktopExcluding, Some(aec)) => aec,
+            (CaptureMode::DesktopExcluding, None) if public_desktop_excluding => {
+                bail!("--audio-mode=desktop-excluding requires --aec=off|pulse-module:<idx>");
+            }
+            (CaptureMode::DesktopExcluding, None) => AecConfig::Off,
+            (CaptureMode::Legacy, Some(_)) => {
+                bail!("--aec requires --audio-mode=desktop-excluding");
+            }
+            (CaptureMode::Legacy, None) => AecConfig::Off,
+        };
 
         Ok(HostOpts {
             window: self.window,
@@ -281,6 +337,7 @@ impl Cli {
             max_viewers: self.max_viewers,
             interactive,
             capture_mode,
+            aec,
             legacy_null_sink,
             relay: crate::common::endpoint::relay_override(self.relay.as_deref()),
         })
@@ -295,6 +352,14 @@ impl Cli {
     }
 }
 
+fn parse_aec_cli(value: &str) -> std::result::Result<AecConfig, String> {
+    parse_aec_arg(value).map_err(|_| {
+        format!(
+            "invalid AEC identity {value:?}; expected `off` or `pulse-module:<unsigned decimal>`"
+        )
+    })
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -337,6 +402,121 @@ mod tests {
             .into_host_opts_with_legacy_override(false, false)
             .expect("non-conflicting hidden mode resolves");
         assert_eq!(opts.capture_mode, CaptureMode::DesktopExcluding);
+        assert_eq!(opts.aec, AecConfig::Off);
         assert!(!opts.legacy_null_sink);
     }
+
+    #[test]
+    fn phase_7_public_contract_is_visible_in_help() {
+        let help = Cli::command().render_long_help().to_string();
+        assert!(help.contains("--audio-mode <MODE>"));
+        assert!(help.contains("desktop-shared"));
+        assert!(help.contains("desktop-excluding"));
+        assert!(help.contains("--aec <off|pulse-module:<idx>>"));
+        assert!(help.contains("--capabilities"));
+    }
+
+    #[test]
+    fn public_desktop_modes_resolve_to_the_typed_planner() {
+        let shared = Cli::try_parse_from(["pixelpass", "--host", "--audio-mode=desktop-shared"])
+            .expect("public shared mode parses")
+            .into_host_opts_with_legacy_override(false, false)
+            .expect("public shared mode resolves");
+        assert_eq!(shared.capture_mode, CaptureMode::Legacy);
+        assert_eq!(shared.aec, AecConfig::Off);
+
+        let excluding = Cli::try_parse_from([
+            "pixelpass",
+            "--host",
+            "--audio-mode=desktop-excluding",
+            "--aec=pulse-module:536870919",
+        ])
+        .expect("public excluding mode parses")
+        .into_host_opts_with_legacy_override(false, false)
+        .expect("public excluding mode resolves");
+        assert_eq!(excluding.capture_mode, CaptureMode::DesktopExcluding);
+        assert_eq!(excluding.aec, AecConfig::PulseModule(536_870_919));
+    }
+
+    #[test]
+    fn public_desktop_excluding_requires_explicit_aec_state() {
+        let cli = Cli::try_parse_from(["pixelpass", "--host", "--audio-mode=desktop-excluding"])
+            .expect("mode token parses before semantic validation");
+        let error = cli
+            .into_host_opts_with_legacy_override(false, false)
+            .expect_err("missing AEC state must fail the public excluding mode");
+        assert!(error.to_string().contains("requires --aec"));
+    }
+
+    #[test]
+    fn public_audio_protocol_flags_require_host_mode() {
+        for args in [
+            ["pixelpass", "--audio-mode=desktop-shared"],
+            ["pixelpass", "--aec=off"],
+        ] {
+            let error = Cli::try_parse_from(args)
+                .expect_err("host-only audio protocol flag parsed without --host");
+            assert_eq!(
+                error.kind(),
+                clap::error::ErrorKind::MissingRequiredArgument
+            );
+        }
+    }
+
+    #[test]
+    fn aec_is_rejected_outside_desktop_excluding_and_malformed_at_parse_time() {
+        let cli = Cli::try_parse_from(["pixelpass", "--host", "--aec=off"])
+            .expect("AEC token parses before mode validation");
+        assert!(
+            cli.into_host_opts_with_legacy_override(false, false)
+                .expect_err("legacy capture must not silently ignore an AEC identity")
+                .to_string()
+                .contains("requires --audio-mode=desktop-excluding")
+        );
+
+        let malformed = Cli::try_parse_from([
+            "pixelpass",
+            "--host",
+            "--audio-mode=desktop-excluding",
+            "--aec=module:7",
+        ])
+        .expect_err("the public CLI must use the Phase-4 exact grammar");
+        assert_eq!(malformed.kind(), clap::error::ErrorKind::ValueValidation);
+    }
+
+    #[test]
+    fn old_peerspeak_host_argv_golden_is_byte_compatible_without_aec() {
+        let whole_desktop = Cli::try_parse_from(["pixelpass", "--host", "--output", "json"])
+            .expect("new PixelPass must accept old whole-desktop argv unchanged")
+            .into_host_opts_with_legacy_override(false, false)
+            .expect("old whole-desktop argv resolves without new flags");
+        assert_eq!(whole_desktop.capture_mode, CaptureMode::Legacy);
+        assert_eq!(whole_desktop.aec, AecConfig::Off);
+        assert!(whole_desktop.app.is_none());
+
+        // Exact argv emitted by PeerSpeak before the Phase-8 integration.
+        let cli = Cli::try_parse_from([
+            "pixelpass",
+            "--host",
+            "--output",
+            "json",
+            "--app=Firefox",
+            "--strict-audio",
+        ])
+        .expect("new PixelPass must accept old PeerSpeak argv unchanged");
+        assert!(cli.host);
+        assert_eq!(cli.output, Some(OutputFormat::Json));
+        assert_eq!(cli.app.as_deref(), Some("Firefox"));
+        assert!(cli.strict_audio);
+        assert!(cli.audio_mode.is_none());
+        assert!(cli.aec.is_none());
+
+        let opts = cli
+            .into_host_opts_with_legacy_override(false, false)
+            .expect("old PeerSpeak argv resolves without new flags");
+        assert_eq!(opts.capture_mode, CaptureMode::Legacy);
+        assert_eq!(opts.aec, AecConfig::Off);
+        assert_eq!(opts.app.as_deref(), Some("Firefox"));
+        assert!(opts.strict_audio);
+    }
 }

src/host/aec/mod.rs

@@ -46,8 +46,6 @@
 //! adapter; this module consumes the already-parsed
 //! [`NodeProps::pulse_module_id`](crate::host::taint::snapshot::NodeProps).
 
-#![allow(dead_code)] // Wired into `--aec` parsing + the recompute loop by later phases.
-
 #[cfg(test)]
 mod tests;
 

src/host/audio.rs

@@ -860,6 +860,7 @@ mod tests {
             max_viewers: None,
             interactive: false,
             capture_mode: crate::cli::CaptureMode::Legacy,
+            aec: crate::host::aec::AecConfig::Off,
             legacy_null_sink: false,
             relay: None,
         }

src/host/audio_plan.rs

@@ -10,12 +10,13 @@
 //!   has no module ledger or loopback constructor.
 //!
 //! Phase 6 feeds the last variant through retained, non-lingering native
-//! PipeWire links. The selector remains the hidden phase-0d trigger until the
-//! public capability and cross-repository protocol land in phases 7–8.
+//! PipeWire links. Phase 7 exposes the typed selector and versioned capability;
+//! Phase 8 is the PeerSpeak-side capability-gated integration.
 
 use anyhow::{Context, Result, bail};
 use tokio::process::Command;
 
+use super::aec::AecConfig;
 use super::audio::Routing;
 use super::graph::BareCaptureSink;
 use super::health;
@@ -28,6 +29,7 @@ trait CapturePlanBackend {
     async fn start_bare_capture_sink(
         &mut self,
         health: health::Reporter,
+        aec: AecConfig,
     ) -> Result<BareCaptureSink>;
 }
 
@@ -49,8 +51,9 @@ impl CapturePlanBackend for SystemCapturePlanBackend {
     async fn start_bare_capture_sink(
         &mut self,
         health: health::Reporter,
+        aec: AecConfig,
     ) -> Result<BareCaptureSink> {
-        BareCaptureSink::start(health).await
+        BareCaptureSink::start(health, aec).await
     }
 }
 
@@ -160,7 +163,7 @@ impl CapturePlan {
             }),
             CapturePlanKind::DesktopExcluding => Ok(Self::DesktopExcluding {
                 capture_sink: backend
-                    .start_bare_capture_sink(health)
+                    .start_bare_capture_sink(health, opts.aec)
                     .await
                     .context("desktop-excluding capture-sink setup failed")?,
             }),
@@ -199,7 +202,6 @@ impl CapturePlan {
 mod tests {
     use super::*;
     use crate::cli::Quality;
-    use crate::host::aec::AecConfig;
     use crate::host::fanout::TestFanoutPolicy;
     use crate::host::observer::{Projection, Readiness};
     use crate::host::taint::fixture::Graph;
@@ -233,6 +235,7 @@ mod tests {
             max_viewers: None,
             interactive: false,
             capture_mode,
+            aec: AecConfig::Off,
             legacy_null_sink,
             relay: None,
         }
@@ -291,6 +294,7 @@ mod tests {
     struct FailingDesktopBackend {
         failure: Option<anyhow::Error>,
         calls: Vec<BackendCall>,
+        seen_aec: Option<AecConfig>,
     }
 
     impl CapturePlanBackend for FailingDesktopBackend {
@@ -311,8 +315,10 @@ mod tests {
         async fn start_bare_capture_sink(
             &mut self,
             _health: health::Reporter,
+            aec: AecConfig,
         ) -> Result<BareCaptureSink> {
             self.calls.push(BackendCall::BareCaptureSink);
+            self.seen_aec = Some(aec);
             Err(self.failure.take().expect("one injected failure"))
         }
     }
@@ -338,8 +344,13 @@ mod tests {
         async fn start_bare_capture_sink(
             &mut self,
             health: health::Reporter,
+            aec: AecConfig,
         ) -> Result<BareCaptureSink> {
-            BareCaptureSink::start_for_phase6_measurement(health, self.aec, self.policy).await
+            assert_eq!(
+                aec, self.aec,
+                "selector must carry the requested AEC config"
+            );
+            BareCaptureSink::start_for_phase6_measurement(health, aec, self.policy).await
         }
     }
 
@@ -352,6 +363,7 @@ mod tests {
         let mut backend = FailingDesktopBackend {
             failure: Some(failure),
             calls: Vec::new(),
+            seen_aec: None,
         };
         let (health, _) = health::channel();
         let error = match CapturePlan::start_with_backend(&opts, health, &mut backend).await {
@@ -359,6 +371,7 @@ mod tests {
             Err(error) => error,
         };
         assert_eq!(backend.calls, vec![BackendCall::BareCaptureSink]);
+        assert_eq!(backend.seen_aec, Some(AecConfig::Off));
         let chain = format!("{error:#}");
         assert!(chain.contains("desktop-excluding capture-sink setup failed"));
         assert!(
@@ -400,6 +413,27 @@ mod tests {
         .await;
     }
 
+    #[tokio::test]
+    async fn public_aec_identity_reaches_the_bare_sink_constructor() {
+        let mut opts = opts(false, false, CaptureMode::DesktopExcluding, false);
+        opts.aec = AecConfig::PulseModule(536_870_919);
+        let mut backend = FailingDesktopBackend {
+            failure: Some(anyhow::anyhow!(
+                "stop after observing the constructor input"
+            )),
+            calls: Vec::new(),
+            seen_aec: None,
+        };
+        let (health, _) = health::channel();
+        let error = match CapturePlan::start_with_backend(&opts, health, &mut backend).await {
+            Ok(_) => panic!("injected backend unexpectedly constructed a plan"),
+            Err(error) => error,
+        };
+        assert!(error.to_string().contains("desktop-excluding"));
+        assert_eq!(backend.calls, vec![BackendCall::BareCaptureSink]);
+        assert_eq!(backend.seen_aec, Some(opts.aec));
+    }
+
     fn pulse_source_exists(name: &str) -> bool {
         std::process::Command::new("pactl")
             .args(["get-source-volume", name])
@@ -978,6 +1012,7 @@ mod tests {
         label: &'static str,
         desktop_dbfs: f64,
         remote_dbfs: f64,
+        remote_floor_dbfs: f64,
     }
 
     struct PulseModuleGuard {
@@ -1439,6 +1474,22 @@ mod tests {
         Ok(20.0 * amplitude.max(1.0e-12).log10())
     }
 
+    fn local_floor_dbfs(raw: &[u8], frequency: f64) -> Result<f64> {
+        // A single coherent projection of stochastic sub-LSB noise can land
+        // in a deep null and is not a stable "control floor". Estimate this
+        // run's actual analysis resolution from nearby frequencies outside the
+        // Hann main lobe, then use the 90th percentile so one quiet bin cannot
+        // manufacture sensitivity the capture did not have.
+        let mut neighbors = Vec::new();
+        for offset in (5..=25).step_by(2) {
+            neighbors.push(tone_dbfs(raw, frequency - f64::from(offset))?);
+            neighbors.push(tone_dbfs(raw, frequency + f64::from(offset))?);
+        }
+        neighbors.sort_by(f64::total_cmp);
+        let rank = (neighbors.len() * 9).div_ceil(10).saturating_sub(1);
+        Ok(neighbors[rank])
+    }
+
     fn any_echo_cancel_module_loaded() -> Result<bool> {
         let output = Command::new("pactl")
             .args(["list", "short", "modules"])
@@ -1458,7 +1509,8 @@ mod tests {
         let module_id = aec.id();
         let (aec_playback_id, aec_playback_name) = wait_for_aec_playback(module_id).await?;
         let capture_sink_name = crate::repair::plan::sink_name_for(std::process::id());
-        let opts = opts(false, false, CaptureMode::DesktopExcluding, false);
+        let mut opts = opts(false, false, CaptureMode::DesktopExcluding, false);
+        opts.aec = AecConfig::PulseModule(module_id);
         let (health, _) = health::channel();
         let mut backend = Phase6MeasurementBackend {
             aec: AecConfig::PulseModule(module_id),
@@ -1513,6 +1565,7 @@ mod tests {
             label: arm.label,
             desktop_dbfs: tone_dbfs(&raw, 440.0)?,
             remote_dbfs: tone_dbfs(&raw, 1_500.0)?,
+            remote_floor_dbfs: local_floor_dbfs(&raw, 1_500.0)?,
         };
 
         if let Some(remote) = remote.as_mut() {
@@ -1545,10 +1598,11 @@ mod tests {
             bail!("{} arm poisoned audio health: {fault}", arm.label);
         }
         eprintln!(
-            "Phase-6 {}: 440 Hz {:.2} dBFS, 1500 Hz {:.2} dBFS; AEC playback node {} ({})",
+            "Phase-6 {}: 440 Hz {:.2} dBFS, 1500 Hz {:.2} dBFS (local floor {:.2} dBFS); AEC playback node {} ({})",
             measurement.label,
             measurement.desktop_dbfs,
             measurement.remote_dbfs,
+            measurement.remote_floor_dbfs,
             aec_playback_name,
             aec_playback_id,
         );
@@ -1599,9 +1653,10 @@ mod tests {
             (guarded.desktop_dbfs - control.desktop_dbfs).abs() <= GUARDED_DESKTOP_DRIFT_DB,
             "guarded desktop level drifted from control: control={control:?}, guarded={guarded:?}"
         );
+        let resolved_control_floor = control.remote_dbfs.max(control.remote_floor_dbfs);
         assert!(
-            guarded.remote_dbfs <= control.remote_dbfs + GUARDED_FLOOR_TOLERANCE_DB,
-            "guarded 1500 Hz energy rose above the control floor: control={control:?}, guarded={guarded:?}"
+            guarded.remote_dbfs <= resolved_control_floor + GUARDED_FLOOR_TOLERANCE_DB,
+            "guarded 1500 Hz energy rose above the locally resolved control floor ({resolved_control_floor:.2} dBFS): control={control:?}, guarded={guarded:?}"
         );
         assert!(
             naive.remote_dbfs >= control.remote_dbfs + POSITIVE_CONTROL_MARGIN_DB

src/host/graph.rs

@@ -160,11 +160,11 @@ pub(super) struct BareCaptureSink {
 }
 
 impl BareCaptureSink {
-    pub(super) async fn start(health: health::Reporter) -> Result<Self> {
-        Self::start_with_controller(health, |capture_sink, status_tx| {
+    pub(super) async fn start(health: health::Reporter, aec: AecConfig) -> Result<Self> {
+        Self::start_with_controller(health, move |capture_sink, status_tx| {
             Box::new(FanoutController::with_status_sender(
                 capture_sink,
-                AecConfig::Off,
+                aec,
                 status_tx,
             ))
         })
@@ -1482,6 +1482,7 @@ mod tests {
             max_viewers: None,
             interactive: false,
             capture_mode: crate::cli::CaptureMode::Legacy,
+            aec: crate::host::aec::AecConfig::Off,
             legacy_null_sink: false,
             relay: None,
         }

src/host/mod.rs

@@ -568,7 +568,7 @@ fn copy_to_clipboard(text: &str) -> bool {
 fn capture_summary(opts: &HostOpts) -> String {
     let mut bits = vec![if opts.window { "window" } else { "fullscreen" }.to_string()];
     if opts.capture_mode == crate::cli::CaptureMode::DesktopExcluding {
-        bits.push("desktop-excluding-audio (internal)".to_string());
+        bits.push("desktop-excluding-audio".to_string());
     } else if let Some(app) = &opts.app {
         if opts.strict_audio {
             bits.push(format!("app-audio={app} (strict)"));
@@ -600,6 +600,7 @@ mod tests {
             max_viewers: None,
             interactive: false,
             capture_mode: crate::cli::CaptureMode::Legacy,
+            aec: crate::host::aec::AecConfig::Off,
             legacy_null_sink: false,
             relay: None,
         }
@@ -629,7 +630,7 @@ mod tests {
         desktop_excluding.capture_mode = crate::cli::CaptureMode::DesktopExcluding;
         assert_eq!(
             capture_summary(&desktop_excluding),
-            "fullscreen + desktop-excluding-audio (internal)"
+            "fullscreen + desktop-excluding-audio"
         );
     }
 

src/host/pipeline.rs

@@ -418,6 +418,7 @@ mod tests {
             max_viewers: None,
             interactive: false,
             capture_mode: CaptureMode::Legacy,
+            aec: crate::host::aec::AecConfig::Off,
             legacy_null_sink: false,
             relay: None,
         }

src/host/quality.rs

@@ -215,6 +215,7 @@ mod tests {
             max_viewers,
             interactive: false,
             capture_mode: crate::cli::CaptureMode::Legacy,
+            aec: crate::host::aec::AecConfig::Off,
             legacy_null_sink: false,
             relay: None,
         }

src/main.rs

@@ -1,3 +1,4 @@
+mod capabilities;
 mod cli;
 mod common;
 mod doctor;
@@ -19,6 +20,10 @@ async fn main() -> Result<()> {
     let cli = Cli::parse();
     init_tracing(cli.verbose);
 
+    if cli.capabilities {
+        return capabilities::run();
+    }
+
     if matches!(cli.output, Some(cli::OutputFormat::Json)) {
         common::output::set_json(true);
     }