docs(aap): Revise PME hypothesis to Personal Medical Equipment

app/src/main/java/eu/darken/capod/main/ui/devicesettings/DeviceSettingsScreen.kt

@@ -403,10 +403,11 @@ fun DeviceSettingsScreen(
                 }
 
                 // PME Config visualization (debug only, opcode 0x53).
-                // The Wireshark dissector calls this "PME Config"; captures so far are
-                // all-zero on in-production firmware, so the bar chart stays hidden in
-                // that case — showing empty bars would imply the device has a flat EQ,
-                // which we don't actually know.
+                // PME = Personal Medical Equipment (hearing-aid band gains for iOS
+                // 18.1+ AirPods Pro 2 hearing-aid mode). The bar chart reuses the
+                // EQ visualization because the data shape (per-ear × per-profile ×
+                // band gains) renders identically; hidden on all-zero payloads, which
+                // just mean the user hasn't configured a hearing-aid profile yet.
                 val pmeConfig = device.pmeConfig
                 if (eu.darken.capod.BuildConfig.DEBUG &&
                     pmeConfig != null &&

app/src/main/java/eu/darken/capod/pods/core/apple/aap/engine/AapSessionEngine.kt

@@ -590,7 +590,7 @@ internal class AapSessionEngine(
             AapMessageType.UARP_DATA.value,                     // 0x004F
             AapMessageType.UNKNOWN_0X50.value,                  // 0x0050
             AapMessageType.SOURCE_CONTEXT.value,                // 0x0052
-            AapMessageType.SET_BAND_EDGES.value,                // 0x0054 (real EQ; distinct from 0x53 PmeConfig which CAPod decodes)
+            AapMessageType.SET_BAND_EDGES.value,                // 0x0054 (neighbouring opcode; distinct from 0x53 PmeConfig/hearing-aid which CAPod decodes)
             AapMessageType.UNKNOWN_0X55.value,                  // 0x0055
             AapMessageType.SLEEP_DETECTION_UPDATE.value,        // 0x0057
             AapMessageType.UNKNOWN_0X58.value,                  // 0x0058

app/src/main/java/eu/darken/capod/pods/core/apple/aap/protocol/AapMessageType.kt

@@ -90,9 +90,11 @@ enum class AapMessageType(val value: Int, val wiresharkName: String) {
     SOURCE_CONTEXT(0x0052, "Source Context"),
 
     /**
-     * PME (Personal Mixing Engine?) config per Wireshark. CAPod decodes this as
-     * 4 × 8 Float32 values (see [AapSetting.PmeConfig]). Real EQ likely lives
-     * at [SET_BAND_EDGES].
+     * PME = Personal Medical Equipment (cf. PPE = Personal Protective Equipment) —
+     * hearing-aid configuration for the iOS 18.1+ hearing-aid feature on AirPods
+     * Pro 2. Decoded as 4 × 8 Float32 values (see [AapSetting.PmeConfig]); see
+     * that data class for the layout rationale. "PME Config" is the label the
+     * Wireshark AAP dissector uses for this opcode.
      */
     PME_CONFIG(0x0053, "PME Config"),
 

app/src/main/java/eu/darken/capod/pods/core/apple/aap/protocol/AapSetting.kt

@@ -164,13 +164,18 @@ sealed class AapSetting {
     }
 
     /**
-     * Payload of message type 0x0053. The Wireshark AAP dissector calls this
-     * "PME Config" (Personal Mixing Engine). CAPod used to label it as EQ
-     * bands, but captures so far show this data is all zeros on in-production
-     * firmware — the real equalizer path is likely 0x0054 "Set Band Edges".
+     * Payload of message type 0x0053 — "PME Config" in the Wireshark AAP dissector.
+     * PME = Personal Medical Equipment (cf. PPE = Personal Protective Equipment):
+     * the hearing-aid configuration for Apple's iOS 18.1+ hearing-aid feature on
+     * AirPods Pro 2.
      *
-     * The payload is decoded as 4 sets × 8 Float32 values until the true schema
-     * is confirmed. Callers should treat all-zero [sets] as "no config reported".
+     * Decoded as 4 × 8 Float32 values — consistent with per-ear × per-profile
+     * audiogram band gains (e.g. L/R × two environment profiles, 8 frequency
+     * bands). CAPod previously called this "EQ bands".
+     *
+     * Callers should treat all-zero [sets] as "no hearing-aid profile configured"
+     * — stock firmware reports zeros until the user runs Apple's Hearing Test /
+     * hearing-aid setup.
      */
     data class PmeConfig(
         val sets: List<List<Float>>,

app/src/main/java/eu/darken/capod/pods/core/apple/aap/protocol/DefaultAapDeviceProfile.kt

@@ -158,10 +158,12 @@ class DefaultAapDeviceProfile(
             return AapSetting.AudioSource::class to AapSetting.AudioSource(mac, type)
         }
 
-        // 0x53 is "PME Config" per the Wireshark AAP dissector. CAPod decodes the
-        // 4-set × 8-band Float32 payload verbatim; captures so far have all-zero
-        // payloads so the schema is unconfirmed. Real EQ likely lives on 0x54
-        // "Set Band Edges" with a different byte layout.
+        // 0x53 is "PME Config" per the Wireshark AAP dissector — Personal Medical
+        // Equipment (cf. PPE), i.e. the iOS 18.1+ hearing-aid profile on AirPods
+        // Pro 2. Decoded verbatim as 4 × 8 Float32 (per-ear × per-profile band
+        // gains); stock firmware reports all-zero until the user runs Apple's
+        // Hearing Test. 0x54 "Set Band Edges" is a neighbouring opcode with a
+        // different payload — not decoded here.
         if (message.commandType == AapMessageType.PME_CONFIG.value) {
             if (message.payload.size < 6 + 128) return null
             val sets = mutableListOf<List<Float>>()