diff --git a/SURFACE_LEVEL_PLAN.md b/SURFACE_LEVEL_PLAN.md
new file mode 100644
index 0000000..19327db
--- /dev/null
+++ b/SURFACE_LEVEL_PLAN.md
@@ -0,0 +1,134 @@
+# Surface Level — Implementation Attack Plan
+
+**Status:** Proposed; send to Claude for audit before implementation.  
+**Scope:** Surface Level only. Do not change Angle, Edge, ruler, or billing in this stage.
+
+## Outcome
+
+Build a trustworthy two-axis surface-level tool for a phone lying flat,
+screen-up, on a surface. It must feel like a physical bullseye vial while
+giving clearer, more actionable information than a physical level.
+
+The user should be able to answer three questions at a glance or by sound:
+
+1. Is this surface level?
+2. How far off is it?
+3. Which side/corner needs adjustment, and by roughly how much?
+
+## Existing foundation to preserve
+
+- Unified device-frame world-up sensor contract.
+- Raw sensor -> stable measurement -> animated display separation.
+- Vector-space Surface calibration model and two-sample calibration math.
+- EMA smoothing, lock hysteresis/dwell/debounce, deadband, and current tests.
+- The current numeric Surface reading, pitch/roll values, and haptic lock hook.
+
+## Product decisions to implement
+
+- Surface means the phone is intended to lie flat, screen-up, on the plane being
+  measured. Its level-lock behavior is valid only in that geometry.
+- Numeric measurements are never hidden because the phone is steeply oriented.
+  Outside the ideal Surface geometry, show the actual angle and a quiet placement
+  hint; suppress level-lock feedback rather than replacing the reading with `—`.
+- The central visualization is a bullseye vial. It has a finite visual range:
+  beyond that range the bubble rests at the rim, while numeric information remains
+  full-range and authoritative.
+- Calibration corrects device/setup bias. It is not "make this desk level."
+  A later relative-reference feature is separate and out of scope here.
+
+## Work sequence
+
+### 1. Make measurement behavior honest at every angle
+
+- Refactor Surface placement gating so it only controls the level-lock state,
+  lock haptic, and geometry-specific guidance.
+- Keep primary angle, pitch, and roll visible at 0-90 degrees.
+- Add tests at flat, near level, 30 degrees, and near vertical proving numeric
+  readings remain present and correct; verify invalid placement never locks.
+- Keep the existing lock tolerance semantics: a lock label states the tolerance
+  rather than pretending any non-zero value is exactly flat.
+
+### 2. Add the guided Surface calibration flow
+
+- Add a Surface Calibration route from the Level header.
+- Explain that the phone may be calibrated on any firm, stable surface; the
+  surface itself does not need to be level.
+- Step 1: settle, sample for a short stable window, capture.
+- Step 2: rotate the phone exactly 180 degrees in the same plane, settle, capture.
+- Reject/retry if readings indicate motion or inconsistent placement.
+- Persist only the resulting Surface calibration; never alter Edge calibration.
+- State that the calibration applies to the current phone/case/contact setup.
+- On completion, show a concise success result and a way to clear/re-run it.
+
+### 3. Build the tactile bullseye instrument
+
+- Use Compose Canvas (or an equivalent composable drawing layer) for a scalable
+  circular vial, etched rings, crosshairs, target zone, and bubble.
+- Glass, fluid, and meniscus effects must improve depth/readability; avoid a
+  decorative or excessively glossy treatment.
+- Bubble target position derives directly from stable calibrated pitch/roll.
+- Bubble movement uses a critically damped animation toward that real target:
+  no random drift, autonomous wobble, or animation that contradicts the number.
+- Respect disabled system animations and the app's reduced-motion preference by
+  minimizing or removing the display spring.
+- Show a large total tilt beside/below the vial, then Pitch and Roll below it.
+- At level lock, use the restrained lime state and an explicit text label.
+
+### 4. Add actionable adjustment information
+
+- Derive a screen-relative high/low direction from calibrated Pitch and Roll.
+  Use language such as `High: lower-left`; do not claim a compass direction.
+- Display slope as both degrees and a useful normalized rise/run value:
+  millimetres per metre and/or inches per foot based on the selected unit system.
+- Treat exact board/counter dimensions and calculated shim/foot height as a later
+  Adjustment Assist feature, not a requirement of this stage.
+- When the reading is moving, show a subtle `Settling` state and defer strong
+  correction guidance until the stable measurement is trustworthy.
+
+### 5. Add optional hands-free Audio Level Assist
+
+- Surface-only, off by default, explicitly user-enabled.
+- Use a soft sonar-like pulse with a gentle attack and naturally fading tail;
+  never a harsh alarm or rapid smoke-detector cadence.
+- Silent while settling or materially outside the usable placement geometry.
+- Near level: occasional low-key proximity pulses.
+- Locked: one distinct soft lock ping; optionally provide a sparse repeat-while-
+  locked preference so a user adjusting a large plank can hear that it remains level.
+- Reuse the existing lock dwell/hysteresis/debounce so sound cannot chatter.
+- Respect media volume, audio focus, system sound settings, app lifecycle, and
+  the user's Audio Assist preference.
+
+## Surface acceptance criteria
+
+- A stable phone on a known level plane achieves lock without repeated feedback.
+- A 180-degree calibration on a stable but non-level plane improves repeatability
+  without zeroing that plane's real slope.
+- A screen-up phone at 30 and near 90 degrees still shows meaningful numbers;
+  it does not falsely claim Surface lock.
+- Bubble direction agrees with Pitch/Roll and with the high/low instruction.
+- Bubble visual remains physically believable but never leads or disagrees with
+  the stable numeric reading.
+- Audio can guide a user to lock without viewing the screen and stays quiet when
+  disabled, settling, backgrounded, or outside the Surface geometry.
+- Manual checks cover phone-with-case, phone-without-case, a firm tabletop, and
+  a large board adjusted by one person.
+
+## Explicitly deferred
+
+- Angle-screen redesign and signed relative-angle semantics.
+- Edge/Plumb visual and geometry changes.
+- Saved measurements, target-angle alerts, screen ruler, and Play Billing.
+- Board dimension/shim calculator and automatic flat/edge switching.
+
+## Questions for Claude's audit
+
+1. Does the relaxed placement gate preserve truthful full-range Surface numbers
+   while preventing false lock feedback?
+2. Is the two-sample calibration flow mathematically and UX-wise safe for the
+   stated use case, including phone cases and non-level calibration surfaces?
+3. Is high/low mapping unambiguous and testable for all pitch/roll quadrants?
+4. Does the bullseye animation remain derived from measurement truth and respect
+   reduced-motion/system-animation settings?
+5. Can the audio state machine reuse lock semantics without audio-focus,
+   lifecycle, or repeated-feedback problems?
+6. Is any proposed work outside this single-stage scope?
diff --git a/gradle/gradle-daemon-jvm.properties b/gradle/gradle-daemon-jvm.properties
new file mode 100644
index 0000000..6c1139e
--- /dev/null
+++ b/gradle/gradle-daemon-jvm.properties
@@ -0,0 +1,12 @@
+#This file is generated by updateDaemonJvm
+toolchainUrl.FREE_BSD.AARCH64=https\://api.foojay.io/disco/v3.0/ids/ec7520a1e057cd116f9544c42142a16b/redirect
+toolchainUrl.FREE_BSD.X86_64=https\://api.foojay.io/disco/v3.0/ids/4c4f879899012ff0a8b2e2117df03b0e/redirect
+toolchainUrl.LINUX.AARCH64=https\://api.foojay.io/disco/v3.0/ids/ec7520a1e057cd116f9544c42142a16b/redirect
+toolchainUrl.LINUX.X86_64=https\://api.foojay.io/disco/v3.0/ids/4c4f879899012ff0a8b2e2117df03b0e/redirect
+toolchainUrl.MAC_OS.AARCH64=https\://api.foojay.io/disco/v3.0/ids/73bcfb608d1fde9fb62e462f834a3299/redirect
+toolchainUrl.MAC_OS.X86_64=https\://api.foojay.io/disco/v3.0/ids/846ee0d876d26a26f37aa1ce8de73224/redirect
+toolchainUrl.UNIX.AARCH64=https\://api.foojay.io/disco/v3.0/ids/ec7520a1e057cd116f9544c42142a16b/redirect
+toolchainUrl.UNIX.X86_64=https\://api.foojay.io/disco/v3.0/ids/4c4f879899012ff0a8b2e2117df03b0e/redirect
+toolchainUrl.WINDOWS.AARCH64=https\://api.foojay.io/disco/v3.0/ids/9482ddec596298c84656d31d16652665/redirect
+toolchainUrl.WINDOWS.X86_64=https\://api.foojay.io/disco/v3.0/ids/39701d92e1756bb2f141eb67cd4c660e/redirect
+toolchainVersion=21