chore: License the project under GPL-3.0-or-later

In preparation for publishing the source publicly: without a license
file the code would default to all-rights-reserved, so nobody could
legally use or modify it. Add the GPL v3 text, a license section in
the README, and REUSE-style SPDX headers in every Kotlin source and
Gradle build script so per-file licensing is machine-readable.

The bundled JetBrains Mono font stays under its own SIL Open Font
License 1.1, whose text must accompany redistribution. OFL.txt lives
at the repo root rather than next to the fonts because aapt rejects
non-font files in res/font.

.gitignore

@@ -12,3 +12,8 @@ local.properties
 
 # Claude Code session data
 .claude/
+
+# Signing credentials — keep off version control
+*.jks
+*.keystore
+keystore.properties

BACKLOG.md

@@ -68,6 +68,10 @@ US-15: As a user, I want an app icon and splash screen so that it feels native.
 US-16: As a developer, I want a signed APK for installation so that the app can be deployed.
 - Acceptance: Release build generated; offline functionality verified.
 
+### Theme 8: Landscape Support
+US-18: As a user, I want the app to work in landscape orientation so that I can use it however I hold my phone.
+- Acceptance: In landscape, all controls are visible and usable without scrolling; layout switches to a two-column arrangement (pulse ring + BPM display on the left, sliders/buttons on the right); no content is clipped or overlapping.
+
 ## Additional Notes
 - TDD: Focus on US-03, US-04, US-13 first—write failing tests, then implement.
 - Priorities: Complete setup (US-01-02), then audio (US-03-05), UI (US-06-07), service (US-08-10), rest.

LICENSE

@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
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+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.

OFL.txt

@@ -0,0 +1,93 @@
+Copyright 2020 The JetBrains Mono Project Authors (https://github.com/JetBrains/JetBrainsMono)
+
+This Font Software is licensed under the SIL Open Font License, Version 1.1.
+This license is copied below, and is also available with a FAQ at:
+https://openfontlicense.org
+
+
+-----------------------------------------------------------
+SIL OPEN FONT LICENSE Version 1.1 - 26 February 2007
+-----------------------------------------------------------
+
+PREAMBLE
+The goals of the Open Font License (OFL) are to stimulate worldwide
+development of collaborative font projects, to support the font creation
+efforts of academic and linguistic communities, and to provide a free and
+open framework in which fonts may be shared and improved in partnership
+with others.
+
+The OFL allows the licensed fonts to be used, studied, modified and
+redistributed freely as long as they are not sold by themselves. The
+fonts, including any derivative works, can be bundled, embedded, 
+redistributed and/or sold with any software provided that any reserved
+names are not used by derivative works. The fonts and derivatives,
+however, cannot be released under any other type of license. The
+requirement for fonts to remain under this license does not apply
+to any document created using the fonts or their derivatives.
+
+DEFINITIONS
+"Font Software" refers to the set of files released by the Copyright
+Holder(s) under this license and clearly marked as such. This may
+include source files, build scripts and documentation.
+
+"Reserved Font Name" refers to any names specified as such after the
+copyright statement(s).
+
+"Original Version" refers to the collection of Font Software components as
+distributed by the Copyright Holder(s).
+
+"Modified Version" refers to any derivative made by adding to, deleting,
+or substituting -- in part or in whole -- any of the components of the
+Original Version, by changing formats or by porting the Font Software to a
+new environment.
+
+"Author" refers to any designer, engineer, programmer, technical
+writer or other person who contributed to the Font Software.
+
+PERMISSION & CONDITIONS
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of the Font Software, to use, study, copy, merge, embed, modify,
+redistribute, and sell modified and unmodified copies of the Font
+Software, subject to the following conditions:
+
+1) Neither the Font Software nor any of its individual components,
+in Original or Modified Versions, may be sold by itself.
+
+2) Original or Modified Versions of the Font Software may be bundled,
+redistributed and/or sold with any software, provided that each copy
+contains the above copyright notice and this license. These can be
+included either as stand-alone text files, human-readable headers or
+in the appropriate machine-readable metadata fields within text or
+binary files as long as those fields can be easily viewed by the user.
+
+3) No Modified Version of the Font Software may use the Reserved Font
+Name(s) unless explicit written permission is granted by the corresponding
+Copyright Holder. This restriction only applies to the primary font name as
+presented to the users.
+
+4) The name(s) of the Copyright Holder(s) or the Author(s) of the Font
+Software shall not be used to promote, endorse or advertise any
+Modified Version, except to acknowledge the contribution(s) of the
+Copyright Holder(s) and the Author(s) or with their explicit written
+permission.
+
+5) The Font Software, modified or unmodified, in part or in whole,
+must be distributed entirely under this license, and must not be
+distributed under any other license. The requirement for fonts to
+remain under this license does not apply to any document created
+using the Font Software.
+
+TERMINATION
+This license becomes null and void if any of the above conditions are
+not met.
+
+DISCLAIMER
+THE FONT SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
+OF COPYRIGHT, PATENT, TRADEMARK, OR OTHER RIGHT. IN NO EVENT SHALL THE
+COPYRIGHT HOLDER BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+INCLUDING ANY GENERAL, SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL
+DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+FROM, OUT OF THE USE OR INABILITY TO USE THE FONT SOFTWARE OR FROM
+OTHER DEALINGS IN THE FONT SOFTWARE.

README.md

@@ -102,3 +102,11 @@ See `BACKLOG.md` for all user stories and acceptance criteria.
 ./gradlew test    # unit tests
 ./gradlew lint    # lint checks
 ```
+
+## License
+
+Pacer is free software, licensed under the GNU General Public License,
+version 3 or (at your option) any later version. See [LICENSE](LICENSE).
+
+The bundled [JetBrains Mono](https://github.com/JetBrains/JetBrainsMono) font
+is licensed under the SIL Open Font License 1.1. See [OFL.txt](OFL.txt).

app/build.gradle.kts

@@ -1,9 +1,19 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+import java.util.Properties
+
 plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.kotlin.android)
     alias(libs.plugins.kotlin.compose)
 }
 
+val keystorePropsFile = rootProject.file("keystore.properties")
+val keystoreProps = Properties().apply {
+    if (keystorePropsFile.exists()) load(keystorePropsFile.inputStream())
+}
+
 android {
     namespace = "net.jeena.pacer"
     compileSdk = 36
@@ -19,9 +29,21 @@ android {
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
 
+    signingConfigs {
+        create("release") {
+            if (keystorePropsFile.exists()) {
+                storeFile = file(keystoreProps["storeFile"] as String)
+                storePassword = keystoreProps["storePassword"] as String
+                keyAlias = keystoreProps["keyAlias"] as String
+                keyPassword = keystoreProps["keyPassword"] as String
+            }
+        }
+    }
+
     buildTypes {
         release {
-            isMinifyEnabled = false
+            isMinifyEnabled = true
+            signingConfig = signingConfigs.getByName("release")
             proguardFiles(
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"

app/src/androidTest/kotlin/net/jeena/pacer/PacerScreenTest.kt

@@ -0,0 +1,71 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package net.jeena.pacer
+
+import androidx.compose.ui.test.assertIsDisplayed
+import androidx.compose.ui.test.junit4.createAndroidComposeRule
+import androidx.compose.ui.test.onNodeWithText
+import androidx.compose.ui.test.performClick
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+/**
+ * Instrumented UI tests for PacerScreen (US-14).
+ * Run with: ./gradlew connectedAndroidTest
+ */
+@RunWith(AndroidJUnit4::class)
+class PacerScreenTest {
+
+    @get:Rule
+    val composeRule = createAndroidComposeRule<MainActivity>()
+
+    @Test
+    fun appLaunches_andShowsStartButton() {
+        composeRule.onNodeWithText("START").assertIsDisplayed()
+    }
+
+    @Test
+    fun appLaunches_andShowsTitle() {
+        composeRule.onNodeWithText("PACER").assertIsDisplayed()
+    }
+
+    @Test
+    fun tappingStart_changesButtonToStop() {
+        composeRule.onNodeWithText("START").performClick()
+        composeRule.onNodeWithText("STOP").assertIsDisplayed()
+    }
+
+    @Test
+    fun tappingStop_changesButtonBackToStart() {
+        composeRule.onNodeWithText("START").performClick()
+        composeRule.onNodeWithText("STOP").performClick()
+        composeRule.onNodeWithText("START").assertIsDisplayed()
+    }
+
+    @Test
+    fun presetButton_updatesBpmDisplay() {
+        // Tap the "100 / SLOW" preset
+        composeRule.onNodeWithText("100").performClick()
+        composeRule.onNodeWithText("100").assertIsDisplayed()
+    }
+
+    @Test
+    fun serviceRunning_afterTappingStart() {
+        composeRule.onNodeWithText("START").performClick()
+        composeRule.waitForIdle()
+        assert(PacerService.isRunning)
+        // Clean up
+        composeRule.onNodeWithText("STOP").performClick()
+    }
+
+    @Test
+    fun serviceStopped_afterTappingStop() {
+        composeRule.onNodeWithText("START").performClick()
+        composeRule.onNodeWithText("STOP").performClick()
+        composeRule.waitForIdle()
+        assert(!PacerService.isRunning)
+    }
+}

app/src/main/kotlin/net/jeena/pacer/AudioEngine.kt

@@ -1,6 +1,10 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import android.media.AudioAttributes
+import kotlin.math.pow
 import android.media.AudioFormat
 import android.media.AudioTrack
 import android.os.Handler
@@ -22,6 +26,17 @@ class AudioEngine {
     companion object {
         private const val BEEP_DURATION_MS = 40
         private const val SILENCE_CHUNK_MS = 10
+
+        // Map the linear 0-1 slider to a perceptually even loudness curve.
+        // AudioTrack.setVolume() takes a linear amplitude, but human hearing
+        // is logarithmic: equal dB steps sound like equal volume steps.
+        // We map the slider to a -40 dB … 0 dB range, so each 25% of travel
+        // changes perceived loudness by the same amount.
+        private fun toAmplitude(linear: Float): Float {
+            if (linear <= 0f) return 0f
+            val db = -40f * (1f - linear)   // 0.0 → -40 dB,  1.0 → 0 dB
+            return 10f.pow(db / 20f)
+        }
     }
 
     private val mainHandler = Handler(Looper.getMainLooper())
@@ -69,7 +84,7 @@ class AudioEngine {
             .setTransferMode(AudioTrack.MODE_STREAM)
             .build()
 
-        audioTrack?.setVolume(currentVolume)
+        audioTrack?.setVolume(toAmplitude(currentVolume))
         audioTrack?.play()
 
         handlerThread = HandlerThread("PacerAudio").also { it.start() }
@@ -94,7 +109,7 @@ class AudioEngine {
 
     fun setVolume(volume: Float) {
         currentVolume = BpmCalculator.clampVolume(volume)
-        audioTrack?.setVolume(currentVolume)
+        audioTrack?.setVolume(toAmplitude(currentVolume))
     }
 
     private fun audioLoop() {

app/src/main/kotlin/net/jeena/pacer/BeepGenerator.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import kotlin.math.sin

app/src/main/kotlin/net/jeena/pacer/BpmCalculator.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 object BpmCalculator {

app/src/main/kotlin/net/jeena/pacer/MainActivity.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import android.content.Intent

app/src/main/kotlin/net/jeena/pacer/PacerService.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import android.app.NotificationChannel

app/src/main/kotlin/net/jeena/pacer/PacerViewModel.kt

@@ -1,18 +1,30 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import android.app.Application
+import android.os.SystemClock
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableFloatStateOf
 import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.setValue
 import androidx.lifecycle.AndroidViewModel
+import androidx.lifecycle.viewModelScope
+import kotlinx.coroutines.Job
+import kotlinx.coroutines.delay
+import kotlinx.coroutines.launch
+import kotlin.math.roundToInt
 
 class PacerViewModel(application: Application) : AndroidViewModel(application) {
 
     private val ctx = application.applicationContext
     private val settings = SettingsRepository(ctx)
 
+    private val tapTimes = mutableListOf<Long>()
+    private var tapResetJob: Job? = null
+
     var bpm by mutableIntStateOf(settings.loadBpm())
         private set
 
@@ -43,4 +55,21 @@ class PacerViewModel(application: Application) : AndroidViewModel(application) {
         settings.saveVolume(newVolume)
         if (isPlaying) ctx.startService(PacerService.updateVolumeIntent(ctx, newVolume))
     }
+
+    fun onTap() {
+        val now = SystemClock.elapsedRealtime()
+        tapTimes.removeAll { now - it > 3000 }
+        tapTimes.add(now)
+
+        if (tapTimes.size >= 2) {
+            val avgInterval = tapTimes.zipWithNext { a, b -> b - a }.average()
+            updateBpm((60000.0 / avgInterval).roundToInt().coerceIn(40, 200))
+        }
+
+        tapResetJob?.cancel()
+        tapResetJob = viewModelScope.launch {
+            delay(2000)
+            tapTimes.clear()
+        }
+    }
 }

app/src/main/kotlin/net/jeena/pacer/SettingsRepository.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import android.content.Context
@@ -20,7 +23,7 @@ class SettingsRepository(context: Context) {
         prefs.edit().putFloat(KEY_VOLUME, volume).apply()
     }
 
-    fun loadBpm(): Int = prefs.getInt(KEY_BPM, 120)
+    fun loadBpm(): Int = prefs.getInt(KEY_BPM, 130)
 
-    fun loadVolume(): Float = prefs.getFloat(KEY_VOLUME, 1f)
+    fun loadVolume(): Float = prefs.getFloat(KEY_VOLUME, 0.6f)
 }

app/src/main/kotlin/net/jeena/pacer/ui/PacerScreen.kt

@@ -1,5 +1,9 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer.ui
 
+import android.content.res.Configuration
 import androidx.compose.animation.core.Animatable
 import androidx.compose.animation.core.LinearEasing
 import androidx.compose.animation.core.tween
@@ -9,9 +13,12 @@ import androidx.compose.foundation.background
 import androidx.compose.foundation.border
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Spacer
+import androidx.compose.foundation.layout.width
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.fillMaxHeight
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
@@ -32,10 +39,10 @@ import androidx.compose.ui.draw.scale
 import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.geometry.Size
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.graphics.RectangleShape
 import androidx.compose.ui.graphics.drawscope.Stroke
 import androidx.compose.ui.graphics.lerp
-import androidx.compose.ui.graphics.RectangleShape
-import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.text.font.FontWeight
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
@@ -105,164 +112,42 @@ fun PacerScreen(viewModel: PacerViewModel, modifier: Modifier = Modifier) {
         }
     }
 
-    val bpmColor = lerp(FG, ACCENT, bpmFlash.value)
+    val bpmColor    = lerp(FG, ACCENT, bpmFlash.value)
+    val stepsPerSec = "%.1f steps/sec".format(bpm / 60.0)
+    val isLandscape = LocalConfiguration.current.orientation == Configuration.ORIENTATION_LANDSCAPE
 
     Box(modifier = modifier.background(BG)) {
 
-        Column(
-            modifier = Modifier
-                .fillMaxSize()
-                .padding(horizontal = 24.dp)
-                .padding(top = 64.dp, bottom = 48.dp),
-            horizontalAlignment = Alignment.CenterHorizontally,
-            verticalArrangement = Arrangement.SpaceBetween
-        ) {
-            // Title
-            Text(
-                text = "PACER",
-                fontSize = 28.sp,
-                fontWeight = FontWeight.Bold,
-                fontFamily = JetBrainsMono,
-                color = ACCENT,
-                letterSpacing = 5.sp
+        if (isLandscape) {
+            LandscapeLayout(
+                isPlaying    = isPlaying,
+                bpm          = bpm,
+                volume       = volume,
+                bpmColor     = bpmColor,
+                stepsPerSec  = stepsPerSec,
+                rippleScale  = rippleScale.value,
+                rippleAlpha  = rippleAlpha.value,
+                dotScale     = dotScale.value,
+                onBpmChange  = { viewModel.updateBpm(it) },
+                onVolChange  = { viewModel.updateVolume(it) },
+                onToggle     = { viewModel.togglePlayback() },
+                onTap        = { viewModel.onTap() }
+            )
+        } else {
+            PortraitLayout(
+                isPlaying    = isPlaying,
+                bpm          = bpm,
+                volume       = volume,
+                bpmColor     = bpmColor,
+                stepsPerSec  = stepsPerSec,
+                rippleScale  = rippleScale.value,
+                rippleAlpha  = rippleAlpha.value,
+                dotScale     = dotScale.value,
+                onBpmChange  = { viewModel.updateBpm(it) },
+                onVolChange  = { viewModel.updateVolume(it) },
+                onToggle     = { viewModel.togglePlayback() },
+                onTap        = { viewModel.onTap() }
             )
-
-            // Pulse ring + ripple + center dot
-            Box(contentAlignment = Alignment.Center, modifier = Modifier.size(80.dp)) {
-                Canvas(modifier = Modifier.fillMaxSize()) {
-                    drawCircle(
-                        color = ACCENT.copy(alpha = rippleAlpha.value),
-                        radius = (size.minDimension / 2f) * rippleScale.value,
-                        style = Stroke(width = 2.dp.toPx())
-                    )
-                }
-                Box(
-                    modifier = Modifier
-                        .size(50.dp)
-                        .border(2.dp, ACCENT, CircleShape)
-                )
-                Box(
-                    modifier = Modifier
-                        .size(12.dp)
-                        .scale(dotScale.value)
-                        .background(ACCENT, CircleShape)
-                )
-            }
-
-            // BPM number
-            Column(horizontalAlignment = Alignment.CenterHorizontally) {
-                Text(
-                    text = "$bpm",
-                    fontSize = 80.sp,
-                    fontWeight = FontWeight.Bold,
-                    fontFamily = JetBrainsMono,
-                    color = bpmColor,
-                    letterSpacing = (-2).sp
-                )
-                Text(
-                    text = "BPM",
-                    fontSize = 11.sp,
-                    fontFamily = JetBrainsMono,
-                    color = FG.copy(alpha = 0.35f),
-                    letterSpacing = 4.sp
-                )
-            }
-
-            // Start/Stop button
-            OutlinedButton(
-                onClick = { viewModel.togglePlayback() },
-                shape = RectangleShape,
-                border = BorderStroke(2.dp, if (isPlaying) ACCENT else FG),
-                colors = ButtonDefaults.outlinedButtonColors(
-                    contentColor = if (isPlaying) BG else FG,
-                    containerColor = if (isPlaying) ACCENT else Color.Transparent
-                )
-            ) {
-                Text(
-                    text = if (isPlaying) "STOP" else "START",
-                    fontSize = 18.sp,
-                    fontWeight = FontWeight.Bold,
-                    fontFamily = JetBrainsMono,
-                    letterSpacing = 3.sp,
-                    modifier = Modifier.padding(horizontal = 16.dp, vertical = 4.dp)
-                )
-            }
-
-            // BPM slider + presets
-            Column(modifier = Modifier.fillMaxWidth()) {
-                Text(
-                    text = "PACE",
-                    fontSize = 10.sp,
-                    fontFamily = JetBrainsMono,
-                    color = FG.copy(alpha = 0.35f),
-                    letterSpacing = 3.sp
-                )
-                Slider(
-                    value = bpm.toFloat(),
-                    onValueChange = { viewModel.updateBpm(it.toInt()) },
-                    valueRange = 40f..200f,
-                    colors = SliderDefaults.colors(
-                        thumbColor = ACCENT,
-                        activeTrackColor = ACCENT,
-                        inactiveTrackColor = DIM
-                    )
-                )
-                Row(
-                    modifier = Modifier.fillMaxWidth(),
-                    horizontalArrangement = Arrangement.SpaceEvenly
-                ) {
-                    PRESETS.forEach { (preset, label) ->
-                        val active = bpm == preset
-                        OutlinedButton(
-                            onClick = { viewModel.updateBpm(preset) },
-                            modifier = Modifier.size(width = 72.dp, height = 48.dp),
-                            shape = RectangleShape,
-                            contentPadding = PaddingValues(0.dp),
-                            border = BorderStroke(1.dp, if (active) ACCENT else DIM),
-                            colors = ButtonDefaults.outlinedButtonColors(
-                                contentColor = if (active) BG else FG.copy(alpha = 0.6f),
-                                containerColor = if (active) ACCENT else Color.Transparent
-                            )
-                        ) {
-                            Column(horizontalAlignment = Alignment.CenterHorizontally) {
-                                Text(
-                                    text = "$preset",
-                                    fontSize = 13.sp,
-                                    fontWeight = FontWeight.Bold,
-                                    fontFamily = JetBrainsMono
-                                )
-                                Text(
-                                    text = label,
-                                    fontSize = 9.sp,
-                                    fontFamily = JetBrainsMono,
-                                    letterSpacing = 1.sp
-                                )
-                            }
-                        }
-                    }
-                }
-            }
-
-            // Volume slider
-            Column(modifier = Modifier.fillMaxWidth()) {
-                Text(
-                    text = "VOLUME  ${(volume * 100).toInt()}%",
-                    fontSize = 10.sp,
-                    fontFamily = JetBrainsMono,
-                    color = FG.copy(alpha = 0.35f),
-                    letterSpacing = 3.sp
-                )
-                Slider(
-                    value = volume,
-                    onValueChange = { viewModel.updateVolume(it) },
-                    valueRange = 0f..1f,
-                    colors = SliderDefaults.colors(
-                        thumbColor = ACCENT,
-                        activeTrackColor = ACCENT,
-                        inactiveTrackColor = DIM
-                    )
-                )
-            }
         }
 
         // Progress bar — fills linearly across one beat interval
@@ -289,3 +174,296 @@ fun PacerScreen(viewModel: PacerViewModel, modifier: Modifier = Modifier) {
         }
     }
 }
+
+@Composable
+private fun PortraitLayout(
+    isPlaying:   Boolean,
+    bpm:         Int,
+    volume:      Float,
+    bpmColor:    Color,
+    stepsPerSec: String,
+    rippleScale: Float,
+    rippleAlpha: Float,
+    dotScale:    Float,
+    onBpmChange: (Int)   -> Unit,
+    onVolChange: (Float) -> Unit,
+    onToggle:    ()      -> Unit,
+    onTap:       ()      -> Unit,
+) {
+    Column(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(horizontal = 24.dp)
+            .padding(top = 64.dp, bottom = 48.dp),
+        horizontalAlignment = Alignment.CenterHorizontally,
+        verticalArrangement = Arrangement.SpaceBetween
+    ) {
+        Title()
+        BpmDisplay(bpm, bpmColor, stepsPerSec)
+        PulseRing(rippleScale, rippleAlpha, dotScale, size = 80.dp)
+        BpmControls(bpm, onBpmChange)
+        VolumeControl(volume, onVolChange)
+        BottomButtons(isPlaying, onToggle, onTap)
+    }
+}
+
+@Composable
+private fun LandscapeLayout(
+    isPlaying:   Boolean,
+    bpm:         Int,
+    volume:      Float,
+    bpmColor:    Color,
+    stepsPerSec: String,
+    rippleScale: Float,
+    rippleAlpha: Float,
+    dotScale:    Float,
+    onBpmChange: (Int)   -> Unit,
+    onVolChange: (Float) -> Unit,
+    onToggle:    ()      -> Unit,
+    onTap:       ()      -> Unit,
+) {
+    Row(
+        modifier = Modifier
+            .fillMaxSize()
+            .padding(horizontal = 24.dp, vertical = 16.dp),
+        horizontalArrangement = Arrangement.spacedBy(24.dp)
+    ) {
+        // Left column: title + BPM + pulse ring
+        Column(
+            modifier = Modifier
+                .weight(1f)
+                .fillMaxHeight(),
+            horizontalAlignment = Alignment.CenterHorizontally,
+            verticalArrangement = Arrangement.SpaceEvenly
+        ) {
+            Title()
+            BpmDisplay(bpm, bpmColor, stepsPerSec)
+            PulseRing(rippleScale, rippleAlpha, dotScale, size = 64.dp)
+        }
+
+        // Right column: sliders + presets + start/stop
+        Column(
+            modifier = Modifier
+                .weight(1f)
+                .fillMaxHeight(),
+            horizontalAlignment = Alignment.CenterHorizontally,
+            verticalArrangement = Arrangement.SpaceBetween
+        ) {
+            BpmControls(bpm, onBpmChange)
+            VolumeControl(volume, onVolChange)
+            BottomButtons(isPlaying, onToggle, onTap)
+        }
+    }
+}
+
+@Composable
+private fun Title() {
+    Text(
+        text = "PACER",
+        fontSize = 28.sp,
+        fontWeight = FontWeight.Bold,
+        fontFamily = JetBrainsMono,
+        color = ACCENT,
+        letterSpacing = 5.sp
+    )
+}
+
+@Composable
+private fun BpmDisplay(bpm: Int, bpmColor: Color, stepsPerSec: String) {
+    Column(horizontalAlignment = Alignment.CenterHorizontally) {
+        Text(
+            text = "$bpm",
+            fontSize = 80.sp,
+            fontWeight = FontWeight.Bold,
+            fontFamily = JetBrainsMono,
+            color = bpmColor,
+            letterSpacing = (-2).sp
+        )
+        Text(
+            text = "STEPS / MIN",
+            fontSize = 13.sp,
+            fontFamily = JetBrainsMono,
+            color = FG.copy(alpha = 0.65f),
+            letterSpacing = 2.sp
+        )
+        Text(
+            text = stepsPerSec.uppercase(),
+            fontSize = 13.sp,
+            fontFamily = JetBrainsMono,
+            color = FG.copy(alpha = 0.5f),
+            letterSpacing = 1.sp
+        )
+    }
+}
+
+@Composable
+private fun PulseRing(rippleScale: Float, rippleAlpha: Float, dotScale: Float, size: androidx.compose.ui.unit.Dp) {
+    Box(contentAlignment = Alignment.Center, modifier = Modifier.size(size)) {
+        Canvas(modifier = Modifier.fillMaxSize()) {
+            drawCircle(
+                color = ACCENT.copy(alpha = rippleAlpha),
+                radius = (this.size.minDimension / 2f) * rippleScale,
+                style = Stroke(width = 2.dp.toPx())
+            )
+        }
+        Box(
+            modifier = Modifier
+                .size(size * 0.625f)
+                .border(2.dp, ACCENT, CircleShape)
+        )
+        Box(
+            modifier = Modifier
+                .size(size * 0.15f)
+                .scale(dotScale)
+                .background(ACCENT, CircleShape)
+        )
+    }
+}
+
+@Composable
+private fun BpmControls(bpm: Int, onBpmChange: (Int) -> Unit) {
+    Column(modifier = Modifier.fillMaxWidth()) {
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.SpaceBetween
+        ) {
+            Text(
+                text = "SLOW",
+                fontSize = 13.sp,
+                fontFamily = JetBrainsMono,
+                color = FG.copy(alpha = 0.65f),
+                letterSpacing = 2.sp
+            )
+            Text(
+                text = "FAST",
+                fontSize = 13.sp,
+                fontFamily = JetBrainsMono,
+                color = FG.copy(alpha = 0.65f),
+                letterSpacing = 2.sp
+            )
+        }
+        Slider(
+            value = bpm.toFloat(),
+            onValueChange = { onBpmChange(it.toInt()) },
+            valueRange = 40f..200f,
+            colors = SliderDefaults.colors(
+                thumbColor = ACCENT,
+                activeTrackColor = ACCENT,
+                inactiveTrackColor = DIM
+            )
+        )
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.SpaceEvenly
+        ) {
+            PRESETS.forEach { (preset, label) ->
+                val active = bpm == preset
+                OutlinedButton(
+                    onClick = { onBpmChange(preset) },
+                    modifier = Modifier.size(width = 72.dp, height = 48.dp),
+                    shape = RectangleShape,
+                    contentPadding = PaddingValues(0.dp),
+                    border = BorderStroke(1.dp, if (active) ACCENT else DIM),
+                    colors = ButtonDefaults.outlinedButtonColors(
+                        contentColor = if (active) BG else FG.copy(alpha = 0.6f),
+                        containerColor = if (active) ACCENT else Color.Transparent
+                    )
+                ) {
+                    Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                        Text(
+                            text = "$preset",
+                            fontSize = 13.sp,
+                            fontWeight = FontWeight.Bold,
+                            fontFamily = JetBrainsMono
+                        )
+                        Text(
+                            text = label.uppercase(),
+                            fontSize = 10.sp,
+                            fontFamily = JetBrainsMono,
+                            letterSpacing = 1.sp
+                        )
+                    }
+                }
+            }
+        }
+    }
+}
+
+@Composable
+private fun VolumeControl(volume: Float, onVolChange: (Float) -> Unit) {
+    Column(modifier = Modifier.fillMaxWidth()) {
+        Row(
+            modifier = Modifier.fillMaxWidth(),
+            horizontalArrangement = Arrangement.SpaceBetween
+        ) {
+            Text(
+                text = "VOL",
+                fontSize = 13.sp,
+                fontFamily = JetBrainsMono,
+                color = FG.copy(alpha = 0.65f),
+                letterSpacing = 2.sp
+            )
+            Text(
+                text = "${(volume * 100).toInt()}%",
+                fontSize = 13.sp,
+                fontFamily = JetBrainsMono,
+                color = FG.copy(alpha = 0.65f),
+                letterSpacing = 2.sp
+            )
+        }
+        Slider(
+            value = volume,
+            onValueChange = { onVolChange(it) },
+            valueRange = 0f..1f,
+            colors = SliderDefaults.colors(
+                thumbColor = ACCENT,
+                activeTrackColor = ACCENT,
+                inactiveTrackColor = DIM
+            )
+        )
+    }
+}
+
+@Composable
+private fun BottomButtons(isPlaying: Boolean, onToggle: () -> Unit, onTap: () -> Unit) {
+    Row(modifier = Modifier.fillMaxWidth(), horizontalArrangement = Arrangement.spacedBy(8.dp)) {
+        OutlinedButton(
+            onClick = onTap,
+            modifier = Modifier.weight(1f),
+            shape = RectangleShape,
+            border = BorderStroke(2.dp, DIM),
+            colors = ButtonDefaults.outlinedButtonColors(
+                contentColor = FG,
+                containerColor = Color.Transparent
+            )
+        ) {
+            Text(
+                text = "TAP",
+                fontSize = 18.sp,
+                fontWeight = FontWeight.Bold,
+                fontFamily = JetBrainsMono,
+                letterSpacing = 3.sp,
+                modifier = Modifier.padding(vertical = 6.dp)
+            )
+        }
+        OutlinedButton(
+            onClick = onToggle,
+            modifier = Modifier.weight(2f),
+            shape = RectangleShape,
+            border = BorderStroke(2.dp, if (isPlaying) ACCENT else FG),
+            colors = ButtonDefaults.outlinedButtonColors(
+                contentColor = if (isPlaying) BG else FG,
+                containerColor = if (isPlaying) ACCENT else Color.Transparent
+            )
+        ) {
+            Text(
+                text = if (isPlaying) "STOP" else "START",
+                fontSize = 18.sp,
+                fontWeight = FontWeight.Bold,
+                fontFamily = JetBrainsMono,
+                letterSpacing = 3.sp,
+                modifier = Modifier.padding(vertical = 6.dp)
+            )
+        }
+    }
+}

app/src/main/kotlin/net/jeena/pacer/ui/theme/Color.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer.ui.theme
 
 import androidx.compose.ui.graphics.Color

app/src/main/kotlin/net/jeena/pacer/ui/theme/Font.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer.ui.theme
 
 import androidx.compose.ui.text.font.Font

app/src/main/kotlin/net/jeena/pacer/ui/theme/Theme.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer.ui.theme
 
 import androidx.compose.material3.MaterialTheme

app/src/main/kotlin/net/jeena/pacer/ui/theme/Type.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer.ui.theme
 
 import androidx.compose.material3.Typography

app/src/main/res/drawable/ic_launcher_background.xml

@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+    <path
+        android:fillColor="#0A0A0A"
+        android:pathData="M0,0 H108 V108 H0 Z" />
+</vector>

app/src/main/res/drawable/ic_launcher_foreground.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="108dp"
+    android:height="108dp"
+    android:viewportWidth="108"
+    android:viewportHeight="108">
+
+    <!-- Outer ring -->
+    <path
+        android:strokeColor="#E8FF47"
+        android:strokeWidth="4"
+        android:fillColor="@android:color/transparent"
+        android:pathData="M54,20 A34,34 0 1,1 53.999,20 Z" />
+
+    <!-- Center dot -->
+    <path
+        android:fillColor="#E8FF47"
+        android:pathData="M54,46 A8,8 0 1,1 53.999,46 Z" />
+
+</vector>

app/src/main/res/mipmap-anydpi-v26/ic_launcher.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

app/src/main/res/mipmap-anydpi-v26/ic_launcher_round.xml

@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<adaptive-icon xmlns:android="http://schemas.android.com/apk/res/android">
+    <background android:drawable="@drawable/ic_launcher_background" />
+    <foreground android:drawable="@drawable/ic_launcher_foreground" />
+</adaptive-icon>

app/src/test/kotlin/net/jeena/pacer/BeepGeneratorTest.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import org.junit.Assert.assertEquals

app/src/test/kotlin/net/jeena/pacer/BpmCalculatorTest.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import org.junit.Assert.assertEquals

app/src/test/kotlin/net/jeena/pacer/SettingsRepositoryTest.kt

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 package net.jeena.pacer
 
 import android.content.Context
@@ -26,8 +29,8 @@ class SettingsRepositoryTest {
 
         prefs = mock()
         whenever(prefs.edit()).thenReturn(editor)
-        whenever(prefs.getInt(eq(SettingsRepository.KEY_BPM), any())).thenReturn(120)
-        whenever(prefs.getFloat(eq(SettingsRepository.KEY_VOLUME), any())).thenReturn(1f)
+        whenever(prefs.getInt(eq(SettingsRepository.KEY_BPM), any())).thenReturn(130)
+        whenever(prefs.getFloat(eq(SettingsRepository.KEY_VOLUME), any())).thenReturn(0.6f)
 
         context = mock()
         whenever(context.getSharedPreferences(any(), any())).thenReturn(prefs)
@@ -62,18 +65,18 @@ class SettingsRepositoryTest {
     }
 
     @Test
-    fun `loadBpm returns default 120 when nothing saved`() {
+    fun `loadBpm returns default 130 when nothing saved`() {
         whenever(prefs.getInt(eq(SettingsRepository.KEY_BPM), any())).thenAnswer {
             it.getArgument(1) as Int
         }
-        assertEquals(120, repo.loadBpm())
+        assertEquals(130, repo.loadBpm())
     }
 
     @Test
-    fun `loadVolume returns default 1f when nothing saved`() {
+    fun `loadVolume returns default 0_6f when nothing saved`() {
         whenever(prefs.getFloat(eq(SettingsRepository.KEY_VOLUME), any())).thenAnswer {
             it.getArgument(1) as Float
         }
-        assertEquals(1f, repo.loadVolume())
+        assertEquals(0.6f, repo.loadVolume())
     }
 }

build.gradle.kts

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 plugins {
     alias(libs.plugins.android.application) apply false
     alias(libs.plugins.kotlin.android) apply false

settings.gradle.kts

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: 2026 Jeena <hello@jeena.net>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 pluginManagement {
     repositories {
         google {