diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 57f7a23..443e87f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,6 +19,7 @@ jobs:
       - run: pnpm install --frozen-lockfile
       - run: pnpm typecheck
       - run: pnpm check:file-length
+      - run: pnpm lint:oxlint
       - run: pnpm lint
       - run: pnpm test:coverage
       - run: pnpm build
diff --git a/.oxlintrc.json b/.oxlintrc.json
new file mode 100644
index 0000000..0bbc96b
--- /dev/null
+++ b/.oxlintrc.json
@@ -0,0 +1,8 @@
+{
+  "$schema": "./node_modules/oxlint/configuration_schema.json",
+  "env": {
+    "browser": true,
+    "node": true
+  },
+  "ignorePatterns": ["dist/**", "dist-demo/**", "coverage/**", "node_modules/**"]
+}
diff --git a/README.md b/README.md
index 20948fd..639cbee 100644
--- a/README.md
+++ b/README.md
@@ -668,12 +668,20 @@ pnpm dev
 
 ```bash
 pnpm typecheck
+pnpm lint:oxlint
 pnpm lint
+pnpm lint:all
+pnpm format:check
 pnpm test
 pnpm test:coverage
 pnpm build
 ```
 
+`pnpm lint:oxlint` 使用 Oxlint 的默认 correctness 检查及内置 TypeScript、Unicorn 和 Oxc
+插件，自动忽略 `dist/`、`dist-demo/`、`coverage/` 和 `node_modules/`。`pnpm lint` 继续负责
+ESLint 的 Vue SFC、TypeScript ESLint 和 `max-lines` 规则；`pnpm lint:all` 会依次运行两者。
+`pnpm format:check` 只读检查 Prettier 格式，`pnpm format` 保持原有的写入行为。
+
 `pnpm build` 同时生成 `dist/` 组件库产物和 `dist-demo/` 演示应用。正式公开入口为
 `src/index.ts`，样式入口为 `src/styles.css`；`dist/` 和 `dist-demo/` 均为生成目录，不要手工编辑。
 
diff --git a/docs/architecture.md b/docs/architecture.md
index 5813268..ff96032 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -1,36 +1,37 @@
 # Architecture
 
-Waveform Analysis uses a hybrid architecture. Vue Composition API remains the orchestration
-boundary, while classes are reserved for domain objects with lifecycle or algorithm-selection
-invariants.
+Waveform Analysis uses a functional architecture around Vue Composition API. Vue composables own
+reactive orchestration and DOM resources, while pure functions own stateless calculations and
+state transitions.
 
 ## Boundaries
 
 - `useWaveformChartController` is the facade for the chart. It composes composables and exposes the
   existing reactive controller surface; it owns no independent copy of component props.
 - `useWaveformViewport` keeps refs, computed values, pointer events, DOM capture, D3 coordinates,
-  and emitted events. `ViewportInteractionStateMachine` is its domain collaborator: it has no Vue
-  or DOM dependency and accepts only legal `begin`, `move`, `finish`, `cancel`, and `reset`
-  transitions. Its state is a `box`/`pan` discriminated union, with `null` representing idle.
-- `RenderablePointSelectionStrategy` defines the replaceable rendering algorithm boundary.
-  `CompletePointSelectionStrategy` preserves the complete visible source range and
-  `PeakPreservingPointSelectionStrategy` preserves first/minimum/maximum/last points per bucket.
-  `resolveRenderablePointSelectionStrategy` resolves and reuses the strategy from rendering options. The
-  existing `selectRenderablePoints` function remains the compatibility facade used by rendering.
+  and emitted events. `transitionViewportInteraction` and `reduceViewportInteraction` are pure
+  reducer functions for the legal `begin`, `move`, `finish`, `cancel`, and `reset` transitions.
+  The composable's `selection` shallow ref is the only interaction state source; SVG overlays and
+  pointer capture remain DOM resources local to the composable.
+- `RenderablePointSelectionStrategy` is a function type defining the replaceable rendering
+  algorithm boundary. `completePointSelectionStrategy` preserves the complete visible source range
+  and `peakPreservingPointSelectionStrategy` preserves first/minimum/maximum/last points per
+  bucket. `resolveRenderablePointSelectionStrategy` selects the function from rendering options.
+  The existing `selectRenderablePoints` function remains the compatibility facade used by rendering.
 - `normalizeWaveformData` and `normalizeWaveformSeries` are functional adapters from public data
   shapes to the internal series model. `buildTrackLayouts` remains a functional builder because
   layout construction is a stateless calculation, not a long-lived object.
 
 ## Vue Integration
 
-The state-machine instance is stored in `shallowRef(markRaw(...))`. Vue receives defensive state
-snapshots through a shallow ref, while SVG overlay elements remain in the composable as DOM
-resources. Presentation mode, annotation editing, scales, domains, ticks, formatting, and other
-stateless calculations stay in their existing computed/composable or function boundaries.
+The viewport `selection` is stored in a shallow ref and updated only with reducer transitions. SVG
+overlay elements remain in the composable as DOM resources. Presentation mode, annotation editing,
+scales, domains, ticks, formatting, and other stateless calculations stay in their existing
+computed/composable or function boundaries.
 
 ## Constraints
 
 Do not create classes solely to wrap Composition API refs, props, lifecycle hooks, D3 selections, or
-pure mathematical helpers. Do not add inheritance trees, global event buses, service locators, or
-duplicate prop state. A new class must own a real invariant or replaceable algorithm and must be
-used by a production path with isolated tests.
+pure mathematical helpers. Do not add strategy factories, inheritance trees, global event buses,
+service locators, or duplicate prop state. Keep pure algorithms and reducer transitions as
+side-effect-free functions with isolated tests.
diff --git a/package.json b/package.json
index 570b38f..ce371be 100644
--- a/package.json
+++ b/package.json
@@ -31,7 +31,10 @@
     "typecheck": "vue-tsc -b",
     "check:file-length": "node scripts/check-file-length.mjs",
     "lint": "eslint . --max-warnings=0",
+    "lint:oxlint": "oxlint . --deny-warnings",
+    "lint:all": "pnpm lint:oxlint && pnpm lint",
     "format": "prettier --write .",
+    "format:check": "prettier --check .",
     "test": "vitest run",
     "test:coverage": "vitest run --coverage"
   },
@@ -57,6 +60,7 @@
     "eslint-plugin-vue": "10.9.2",
     "globals": "17.7.0",
     "jsdom": "29.1.1",
+    "oxlint": "1.77.0",
     "prettier": "3.9.5",
     "typescript": "~6.0.0",
     "typescript-eslint": "8.64.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 5cd7021..fc15dab 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -54,6 +54,9 @@ importers:
       jsdom:
         specifier: 29.1.1
         version: 29.1.1
+      oxlint:
+        specifier: 1.77.0
+        version: 1.77.0
       prettier:
         specifier: 3.9.5
         version: 3.9.5
@@ -279,6 +282,128 @@ packages:
   '@oxc-project/types@0.139.0':
     resolution: {integrity: sha512-r9gHphtCs+1M7J0pw6Sn/hh/Wpa/iQrOOkrNAlVLF/gHq+/CJmHIWKKUUhdWjcD6CIa8idarspCsASiXCXvFUw==}
 
+  '@oxlint/binding-android-arm-eabi@1.77.0':
+    resolution: {integrity: sha512-E06sKWS6PiI6HRxS1wyQg22HvApt01hI7fV+T3wUk3OSbaaP4a3hYGY/MIQDmASqCiRjBdpRQYkgMkqH82cWmQ==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm]
+    os: [android]
+
+  '@oxlint/binding-android-arm64@1.77.0':
+    resolution: {integrity: sha512-NvsKz0KZxTp9cYWPLf+FXaSZwB3oO3peAjtukpOMBgse2vhQSoIIVqeO1yR0lEo/UcdZIDL18uq+kL0LzQ0ytA==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm64]
+    os: [android]
+
+  '@oxlint/binding-darwin-arm64@1.77.0':
+    resolution: {integrity: sha512-bgjTn6nW4bQCFBvSvuHCpDD+sONvmpo4lGI4PxzMt1quBA+xYxhczk6RiCn3GZ9gY8uhaBbwhj9MdKGfu6T9DA==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm64]
+    os: [darwin]
+
+  '@oxlint/binding-darwin-x64@1.77.0':
+    resolution: {integrity: sha512-aotaIttH1R6j1Rwhx0M0htgeZyGtVQqYNTVEYMN/UcgHPquGA6kmk9OyuDc3a2GKUQBC+3C3GVQCcrRPMYqAFA==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [x64]
+    os: [darwin]
+
+  '@oxlint/binding-freebsd-x64@1.77.0':
+    resolution: {integrity: sha512-nNx/wta7ksRAdYvq+l4AWjXkLxEXHALhENxjj2cYbQAIR4ybaA5L+hCbE63HOmft5czQ6ks+hb8vmEAnn7YGPg==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [x64]
+    os: [freebsd]
+
+  '@oxlint/binding-linux-arm-gnueabihf@1.77.0':
+    resolution: {integrity: sha512-tMLLjM7xXtzXisVCzkOTXNCy9bZVId2wteNwjohlFDR/jY6WagpEDA1c1wu4xRc20Hojaxj+V6DSR7gbKxijWA==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm]
+    os: [linux]
+
+  '@oxlint/binding-linux-arm-musleabihf@1.77.0':
+    resolution: {integrity: sha512-MiAFDFaqR0tmHTAyo0YDcZ5hyLREdYw/RQhc2R3cbT+8O3tB+zqPM2th9TTQ+Uo3jn/embS+DO+HyX9ztCPkOQ==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm]
+    os: [linux]
+
+  '@oxlint/binding-linux-arm64-gnu@1.77.0':
+    resolution: {integrity: sha512-/xqQ3B16i1T4cyt/9Mn+4CpzhUXoBXp7kVpIwzOXNFLj5JmK1bIjsbSnX296Gg8A/o7oDtKWikFgBx0SLwztkw==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm64]
+    os: [linux]
+    libc: [glibc]
+
+  '@oxlint/binding-linux-arm64-musl@1.77.0':
+    resolution: {integrity: sha512-LSbwuRKiNCenPDcbARqAZ5RfBy7gmj7vOvfJRLeCDU3gFtSxWbhv/+VTlaUqzUhNj1gFLHB8h7ALnxa/Az6z6g==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm64]
+    os: [linux]
+    libc: [musl]
+
+  '@oxlint/binding-linux-ppc64-gnu@1.77.0':
+    resolution: {integrity: sha512-QWdcH31mXEUe5Nq1s0CfCpceaKjIo9uZtwDjAuL681g1axf+5x8xrg/eXWaw//4NCxYZ4V4e5Hu5tvdR+pTBlg==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [ppc64]
+    os: [linux]
+    libc: [glibc]
+
+  '@oxlint/binding-linux-riscv64-gnu@1.77.0':
+    resolution: {integrity: sha512-GnOfYgJxbcElOiPZaDFDl406ONddwvOWk2jvAAAEjwAl4GofNoHF+/HHUIBYa6bFCArlcGPi0XjC4cU1pkgF/Q==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [riscv64]
+    os: [linux]
+    libc: [glibc]
+
+  '@oxlint/binding-linux-riscv64-musl@1.77.0':
+    resolution: {integrity: sha512-AyEMTUCf0xY+hHF+IxqXFQIX0yQOIR8ykpY0lJNOw9xYqOzUX8dyZfRvlG0RfXwuQn2eonf/8NrMmDSZJjdqsA==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [riscv64]
+    os: [linux]
+    libc: [musl]
+
+  '@oxlint/binding-linux-s390x-gnu@1.77.0':
+    resolution: {integrity: sha512-sPLzEcNvxd/oyVQ5oZo92CiHkFkpBeRop13E/P3TPY+hZfXHKCOWKI70TE2RYwMKFJDc20EMjH16L7NZICtKTw==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [s390x]
+    os: [linux]
+    libc: [glibc]
+
+  '@oxlint/binding-linux-x64-gnu@1.77.0':
+    resolution: {integrity: sha512-1Oh2ssH2L7lwyvkdSqaMUfsGfwU2Wfvew+obBUYjRVqhpBcUpwnsPSEr1IzVi9XqkuY10geiLsNKecqaZC34Dw==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [x64]
+    os: [linux]
+    libc: [glibc]
+
+  '@oxlint/binding-linux-x64-musl@1.77.0':
+    resolution: {integrity: sha512-0j/2wRgNGO+Qj/M1uu/p57h/hFTTWWcfie0ufkbabeus2s5+/QqkCflnMOwLLN5m2GsNeWp4xdl4cPa4n7QCOQ==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [x64]
+    os: [linux]
+    libc: [musl]
+
+  '@oxlint/binding-openharmony-arm64@1.77.0':
+    resolution: {integrity: sha512-BJ/j54qS0usEnyDkLYURMj2iiD9h5Cyy+ppzeMSXBGRXaGRNWnj1Mw14NqWMR5E/PzdgB30OOCCzLzbRoduafw==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm64]
+    os: [openharmony]
+
+  '@oxlint/binding-win32-arm64-msvc@1.77.0':
+    resolution: {integrity: sha512-Yh8w+g2Lpx7StrvtYkoz9JJvXjB9wxgFChFNb85nrXm/wj/XTwGWS1hve9+900HL7llrntYB3YP+y32E3tRqzA==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [arm64]
+    os: [win32]
+
+  '@oxlint/binding-win32-ia32-msvc@1.77.0':
+    resolution: {integrity: sha512-zja5b7+6a7UsRFgAQSrnax5vrzliEyNPLCjfXONu/vTWswaIVZGFajJZptaeRvPE4LghtFdAzVFlexTm7MVTGA==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [ia32]
+    os: [win32]
+
+  '@oxlint/binding-win32-x64-msvc@1.77.0':
+    resolution: {integrity: sha512-+teyvPDZ2RjUvo+SuCqS/UhaJl1QtdW5fWT5NJTV61V5MIuIS90Db9LixmtEGvXixyttiK62P96MSu3UlpviBw==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    cpu: [x64]
+    os: [win32]
+
   '@pkgjs/parseargs@0.11.0':
     resolution: {integrity: sha512-+1VkjdD0QBLPodGrJUeqarH8VAIvQODIbwh9XpP5Syisf7YoQgsJKPNFoqqLQlu+VQ/tVSshMR6loPMn8U+dPg==}
     engines: {node: '>=14'}
@@ -1385,6 +1510,19 @@ packages:
     resolution: {integrity: sha512-6IpQ7mKUxRcZNLIObR0hz7lxsapSSIYNZJwXPGeF0mTVqGKFIXj1DQcMoT22S3ROcLyY/rz0PWaWZ9ayWmad9g==}
     engines: {node: '>= 0.8.0'}
 
+  oxlint@1.77.0:
+    resolution: {integrity: sha512-qnGh8XJHaQ0dprrDXNQZgS0FgjI6v+V3+X8DwmaV++5Aamy6jGKfDdQ1TUvhUxtmKFAbEf4/WeO5QZX+5WSngg==}
+    engines: {node: ^20.19.0 || >=22.12.0}
+    hasBin: true
+    peerDependencies:
+      oxlint-tsgolint: '>=7.0.2001'
+      vite-plus: '*'
+    peerDependenciesMeta:
+      oxlint-tsgolint:
+        optional: true
+      vite-plus:
+        optional: true
+
   p-limit@3.1.0:
     resolution: {integrity: sha512-TYOanM3wGwNGsZN2cVTYPArw454xnXj5qmWF1bEoAc4+cU/ol7GVh7odevjp1FNHduHc3KZMcFduxU5Xc6uJRQ==}
     engines: {node: '>=10'}
@@ -1989,6 +2127,63 @@ snapshots:
 
   '@oxc-project/types@0.139.0': {}
 
+  '@oxlint/binding-android-arm-eabi@1.77.0':
+    optional: true
+
+  '@oxlint/binding-android-arm64@1.77.0':
+    optional: true
+
+  '@oxlint/binding-darwin-arm64@1.77.0':
+    optional: true
+
+  '@oxlint/binding-darwin-x64@1.77.0':
+    optional: true
+
+  '@oxlint/binding-freebsd-x64@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-arm-gnueabihf@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-arm-musleabihf@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-arm64-gnu@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-arm64-musl@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-ppc64-gnu@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-riscv64-gnu@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-riscv64-musl@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-s390x-gnu@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-x64-gnu@1.77.0':
+    optional: true
+
+  '@oxlint/binding-linux-x64-musl@1.77.0':
+    optional: true
+
+  '@oxlint/binding-openharmony-arm64@1.77.0':
+    optional: true
+
+  '@oxlint/binding-win32-arm64-msvc@1.77.0':
+    optional: true
+
+  '@oxlint/binding-win32-ia32-msvc@1.77.0':
+    optional: true
+
+  '@oxlint/binding-win32-x64-msvc@1.77.0':
+    optional: true
+
   '@pkgjs/parseargs@0.11.0':
     optional: true
 
@@ -3143,6 +3338,28 @@ snapshots:
       type-check: 0.4.0
       word-wrap: 1.2.5
 
+  oxlint@1.77.0:
+    optionalDependencies:
+      '@oxlint/binding-android-arm-eabi': 1.77.0
+      '@oxlint/binding-android-arm64': 1.77.0
+      '@oxlint/binding-darwin-arm64': 1.77.0
+      '@oxlint/binding-darwin-x64': 1.77.0
+      '@oxlint/binding-freebsd-x64': 1.77.0
+      '@oxlint/binding-linux-arm-gnueabihf': 1.77.0
+      '@oxlint/binding-linux-arm-musleabihf': 1.77.0
+      '@oxlint/binding-linux-arm64-gnu': 1.77.0
+      '@oxlint/binding-linux-arm64-musl': 1.77.0
+      '@oxlint/binding-linux-ppc64-gnu': 1.77.0
+      '@oxlint/binding-linux-riscv64-gnu': 1.77.0
+      '@oxlint/binding-linux-riscv64-musl': 1.77.0
+      '@oxlint/binding-linux-s390x-gnu': 1.77.0
+      '@oxlint/binding-linux-x64-gnu': 1.77.0
+      '@oxlint/binding-linux-x64-musl': 1.77.0
+      '@oxlint/binding-openharmony-arm64': 1.77.0
+      '@oxlint/binding-win32-arm64-msvc': 1.77.0
+      '@oxlint/binding-win32-ia32-msvc': 1.77.0
+      '@oxlint/binding-win32-x64-msvc': 1.77.0
+
   p-limit@3.1.0:
     dependencies:
       yocto-queue: 0.1.0
diff --git a/src/components/core/useWaveformChartController.ts b/src/components/core/useWaveformChartController.ts
index d0aace1..ef882d2 100644
--- a/src/components/core/useWaveformChartController.ts
+++ b/src/components/core/useWaveformChartController.ts
@@ -18,7 +18,6 @@ import { useWaveformChartAnnotations } from '../annotation/useWaveformChartAnnot
 import { useWaveformHover } from '../interaction/useWaveformHover'
 import { useWaveformViewport } from '../interaction/useWaveformViewport'
 import { useWaveformZoom } from '../interaction/useWaveformZoom'
-import { ViewportInteractionStateMachine } from '../interaction/viewportInteractionState'
 import { useAnimationFrameThrottle } from '../utils/useAnimationFrameThrottle'
 import { margin } from './constants'
 import { getPageSize } from './grid'
@@ -80,7 +79,6 @@ export function useWaveformChartController(
     { deep: true },
   )
   const selection = shallowRef<ViewportSelectionState | null>(null)
-  const viewportInteraction = shallowRef(markRaw(new ViewportInteractionStateMachine()))
   const spacePressed = ref(false)
   const pointerInsideChart = ref(false)
   let handleDataReferenceChange: () => void = () => undefined
@@ -195,7 +193,6 @@ export function useWaveformChartController(
     props,
     emit,
     selection,
-    viewportInteraction,
     spacePressed,
     trackLayouts,
     chartTracks,
diff --git a/src/components/interaction/WaveformTooltip.test.ts b/src/components/interaction/WaveformTooltip.test.ts
index 38489bf..4dbf71c 100644
--- a/src/components/interaction/WaveformTooltip.test.ts
+++ b/src/components/interaction/WaveformTooltip.test.ts
@@ -38,9 +38,48 @@ describe('WaveformTooltip', () => {
     const tooltip = mountTooltip(100, 200).get('.waveform-tooltip')
 
     expect(tooltip.attributes('style')).toContain('left: 8px')
+    expect(tooltip.attributes('style')).toContain('max-width: 184px')
     expect(tooltip.attributes('style')).not.toContain('right:')
   })
 
+  it('keeps short content content-sized while exposing the available width cap', () => {
+    const tooltip = mountTooltip(100).get('.waveform-tooltip')
+
+    expect(tooltip.attributes('style')).toContain('left: 112px')
+    expect(tooltip.attributes('style')).toContain('max-width: 280px')
+  })
+
+  it('keeps long series content in a wrapping content container', () => {
+    const longName = 'ENG8KJXAc-very-long-series-name-10001'
+    const pointWithErrors = { x: 1, y: 12, error: 1, upperError: 2 }
+    const wrapper = mount(WaveformTooltip, {
+      props: {
+        visible: true,
+        position: { x: 100, y: 100 },
+        timeUnit: 'ms',
+        hoveredPoint: pointWithErrors,
+        seriesPoints: [
+          {
+            trackIndex: 0,
+            name: longName,
+            color: '#f00',
+            unit: 'very-long-unit',
+            point: pointWithErrors,
+          },
+        ],
+        containerWidth: 400,
+        containerHeight: 300,
+      },
+    })
+
+    const tooltip = wrapper.get('.waveform-tooltip')
+    expect(tooltip.get('.waveform-tooltip__series-content').text()).toContain(longName)
+    expect(tooltip.get('.waveform-tooltip__series-content').classes()).toContain(
+      'waveform-tooltip__series-content',
+    )
+    expect(tooltip.attributes('style')).toContain('max-width: 280px')
+  })
+
   it('shows resolved asymmetric errors beside the hovered value', () => {
     const pointWithErrors = { x: 1, y: 12, error: 1, upperError: 2 }
     const wrapper = mount(WaveformTooltip, {
diff --git a/src/components/interaction/WaveformTooltip.vue b/src/components/interaction/WaveformTooltip.vue
index 79fc3d9..9bd7a5f 100644
--- a/src/components/interaction/WaveformTooltip.vue
+++ b/src/components/interaction/WaveformTooltip.vue
@@ -33,24 +33,68 @@ const props = defineProps<Props>()
 
 const tooltipGap = 12
 const containerPadding = 8
-const tooltipMaxWidth = 238
+const tooltipPlacementWidth = 238
+const tooltipMaxWidth = 320
+const tooltipHorizontalPadding = 20
+const tooltipLineHeight = 20
+
+function estimateLineCount(text: string, width: number): number {
+  const contentWidth = Math.max(1, width - tooltipHorizontalPadding - 14)
+  const charactersPerLine = Math.max(1, Math.floor(contentWidth / 7.2))
+  return Math.max(1, Math.ceil([...text].length / charactersPerLine))
+}
+
+function formatSeriesText(seriesPoint: SeriesPoint): string {
+  const error = formatError(seriesPoint.point)
+  return `${seriesPoint.name ? `${seriesPoint.name}: ` : ''}${formatTooltipNumber(seriesPoint.point.y)}${
+    seriesPoint.unit ? ` ${seriesPoint.unit}` : ''
+  }${error ? ` ${error}` : ''}`
+}
+
+function estimateTooltipHeight(width: number, timeText: string): number {
+  const seriesLines = props.seriesPoints.reduce(
+    (total, seriesPoint) => total + estimateLineCount(formatSeriesText(seriesPoint), width),
+    0,
+  )
+  return 16 + tooltipLineHeight * (estimateLineCount(timeText, width) + seriesLines) + 5
+}
 
 const tooltipStyle = computed(() => {
   if (!props.visible || !props.hoveredPoint) return { display: 'none' }
 
-  const estimatedHeight = 44 + props.seriesPoints.length * 22
   const rightPlacement = props.position.x + tooltipGap
-  const leftPlacement = props.position.x - tooltipGap - tooltipMaxWidth
+  const leftPlacement = props.position.x - tooltipGap - tooltipPlacementWidth
+  const rightAvailableWidth = props.containerWidth - containerPadding - rightPlacement
+  const leftAvailableWidth = props.position.x - tooltipGap - containerPadding
+  const availableWidth = Math.max(
+    1,
+    Math.min(tooltipMaxWidth, props.containerWidth - containerPadding * 2),
+  )
   const horizontalStyle =
-    rightPlacement + tooltipMaxWidth <= props.containerWidth - containerPadding
-      ? { left: `${rightPlacement}px` }
+    rightPlacement + tooltipPlacementWidth <= props.containerWidth - containerPadding
+      ? {
+          left: `${rightPlacement}px`,
+          maxWidth: `${Math.min(tooltipMaxWidth, rightAvailableWidth)}px`,
+        }
       : leftPlacement >= containerPadding
-        ? { right: `${props.containerWidth - props.position.x + tooltipGap}px` }
-        : { left: `${containerPadding}px` }
+        ? {
+            right: `${props.containerWidth - props.position.x + tooltipGap}px`,
+            maxWidth: `${Math.min(tooltipMaxWidth, leftAvailableWidth)}px`,
+          }
+        : { left: `${containerPadding}px`, maxWidth: `${availableWidth}px` }
+
+  const maxWidth = Number.parseFloat(horizontalStyle.maxWidth)
+  const timeText = `${props.timeUnit}: ${formatTooltipTime(props.hoveredPoint.x, props.timeUnit)}`
 
   return {
     ...horizontalStyle,
-    top: `${Math.max(8, Math.min(props.position.y - 18, props.containerHeight - estimatedHeight - 8))}px`,
+    top: `${Math.max(
+      8,
+      Math.min(
+        props.position.y - 18,
+        props.containerHeight - estimateTooltipHeight(maxWidth, timeText) - 8,
+      ),
+    )}px`,
   }
 })
 
@@ -76,11 +120,13 @@ function formatError(point: WaveformPoint): string | null {
       class="waveform-tooltip__series waveform-chart__tooltip-series"
     >
       <i :style="{ backgroundColor: seriesPoint.color }" />
-      <strong v-if="seriesPoint.name">{{ seriesPoint.name }}:</strong>
-      <span class="waveform-tooltip__value">
-        {{ formatTooltipNumber(seriesPoint.point.y)
-        }}{{ seriesPoint.unit ? ` ${seriesPoint.unit}` : '' }}
-        <small v-if="formatError(seriesPoint.point)">{{ formatError(seriesPoint.point) }}</small>
+      <span class="waveform-tooltip__series-content">
+        <strong v-if="seriesPoint.name">{{ seriesPoint.name }}:</strong>
+        <span class="waveform-tooltip__value">
+          {{ formatTooltipNumber(seriesPoint.point.y)
+          }}{{ seriesPoint.unit ? ` ${seriesPoint.unit}` : '' }}
+          <small v-if="formatError(seriesPoint.point)">{{ formatError(seriesPoint.point) }}</small>
+        </span>
       </span>
     </span>
   </div>
@@ -93,8 +139,8 @@ function formatError(point: WaveformPoint): string | null {
   z-index: 2;
   display: grid;
   gap: 3px;
-  min-width: 180px;
-  max-width: 238px;
+  width: max-content;
+  max-width: min(320px, calc(100% - 16px));
   padding: 8px 10px;
   color: #333;
   font:
@@ -116,30 +162,34 @@ function formatError(point: WaveformPoint): string | null {
 
 .waveform-tooltip__series {
   display: grid;
-  grid-template-columns: 8px minmax(0, 1fr) auto;
+  grid-template-columns: 8px minmax(0, 1fr);
   gap: 6px;
-  align-items: center;
+  align-items: start;
 }
 
 .waveform-tooltip__series i {
+  flex: 0 0 auto;
   width: 8px;
   height: 8px;
+  margin-top: 4px;
   border-radius: 50%;
 }
 
+.waveform-tooltip__series-content {
+  min-width: 0;
+  overflow-wrap: anywhere;
+  white-space: normal;
+}
+
 .waveform-tooltip__series strong {
-  overflow: hidden;
   font-weight: 600;
-  text-overflow: ellipsis;
-  white-space: nowrap;
 }
 
 .waveform-tooltip__value {
-  white-space: nowrap;
+  overflow-wrap: anywhere;
 }
 
 .waveform-tooltip__series small {
   color: #667085;
-  white-space: nowrap;
 }
 </style>
diff --git a/src/components/interaction/pointerCapture.ts b/src/components/interaction/pointerCapture.ts
new file mode 100644
index 0000000..3108018
--- /dev/null
+++ b/src/components/interaction/pointerCapture.ts
@@ -0,0 +1,10 @@
+export function tryReleasePointerCapture(
+  target: SVGRectElement | null | undefined,
+  pointerId: number,
+): void {
+  try {
+    target?.releasePointerCapture?.(pointerId)
+  } catch {
+    // The target may already be detached or have released the pointer.
+  }
+}
diff --git a/src/components/interaction/useWaveformViewport.ts b/src/components/interaction/useWaveformViewport.ts
index 0226b4c..8c6b790 100644
--- a/src/components/interaction/useWaveformViewport.ts
+++ b/src/components/interaction/useWaveformViewport.ts
@@ -1,6 +1,5 @@
 import { pointer, scaleLinear, zoomIdentity, type ZoomTransform } from 'd3'
 import { computed, nextTick, shallowRef, type ComputedRef, type Ref, type ShallowRef } from 'vue'
-
 import { MINIMUM_SELECTION_SIZE } from '../core/constants'
 import type { DisplayTrack, TrackLayout } from '../core/types'
 import { hasFixedYDomainForTrack } from '../core/yDomain'
@@ -10,13 +9,12 @@ import type {
   WaveformChartEmit,
 } from '../core/waveformChartTypes'
 import type { AnnotationSeriesCandidate } from '../annotation'
-import type { ViewportInteractionStateMachine } from './viewportInteractionState'
-
+import { tryReleasePointerCapture } from './pointerCapture'
+import { transitionViewportInteraction } from './viewportInteractionState'
 interface ViewportContext {
   props: ResolvedWaveformChartProps
   emit: WaveformChartEmit
   selection: Ref<ViewportSelectionState | null>
-  viewportInteraction: ShallowRef<ViewportInteractionStateMachine>
   spacePressed: Ref<boolean>
   trackLayouts: ComputedRef<TrackLayout[]>
   chartTracks: ComputedRef<DisplayTrack[]>
@@ -39,13 +37,11 @@ interface ViewportContext {
   clearHover: () => void
   resolveTrackAtPointer: (pointerX: number, pointerY: number) => TrackLayout | undefined
 }
-
 export function useWaveformViewport(context: ViewportContext) {
   const {
     props,
     emit,
     selection,
-    viewportInteraction,
     spacePressed,
     trackLayouts,
     chartTracks,
@@ -69,8 +65,21 @@ export function useWaveformViewport(context: ViewportContext) {
     resolveTrackAtPointer,
   } = context
   const activeOverlay = shallowRef<SVGRectElement>()
-  const syncSelection = () => {
-    selection.value = viewportInteraction.value.state
+  const releasePointerCapture = (pointerId: number, event?: PointerEvent) => {
+    const overlay = activeOverlay.value
+    const eventTarget = event?.currentTarget as SVGRectElement | null
+    tryReleasePointerCapture(overlay, pointerId)
+    if (eventTarget && eventTarget !== overlay) tryReleasePointerCapture(eventTarget, pointerId)
+  }
+  const cleanupViewportDrag = (pointerId: number, event?: PointerEvent) => {
+    const active = selection.value
+    if (!active || active.pointerId !== pointerId) return
+    releasePointerCapture(pointerId, event)
+    selection.value = transitionViewportInteraction(selection.value, {
+      type: 'cancel',
+      pointerId,
+    }).state
+    activeOverlay.value = undefined
   }
   const selectionBox = computed(() => {
     const active = selection.value
@@ -150,19 +159,22 @@ export function useWaveformViewport(context: ViewportContext) {
     const [rawX, rawY] = pointer(event, overlay)
     const x = Math.max(0, Math.min(independent ? track.width : innerWidth.value, rawX))
     const y = Math.max(0, Math.min(independent ? track.height : innerHeight.value, rawY))
-    const started = viewportInteraction.value.begin({
-      trackIndex,
-      independent,
-      startX: x,
-      startY: y,
-      pointerId: event.pointerId,
-      kind: panRequested ? 'pan' : 'box',
-      xDomain: track.xScale.domain() as [number, number],
-      yDomains: currentYDomains(),
+    const started = transitionViewportInteraction(selection.value, {
+      type: 'begin',
+      gesture: {
+        trackIndex,
+        independent,
+        startX: x,
+        startY: y,
+        pointerId: event.pointerId,
+        kind: panRequested ? 'pan' : 'box',
+        xDomain: track.xScale.domain() as [number, number],
+        yDomains: currentYDomains(),
+      },
     })
-    if (!started) return
+    if (!started.accepted) return
+    selection.value = started.state
     activeOverlay.value = overlay
-    syncSelection()
     overlay.setPointerCapture?.(event.pointerId)
     clearHover()
     event.preventDefault()
@@ -233,8 +245,13 @@ export function useWaveformViewport(context: ViewportContext) {
       0,
       Math.min(active.independent ? track.height : innerHeight.value, rawY),
     )
-    const next = viewportInteraction.value.move(event.pointerId, { currentX, currentY })
-    if (!next) return
+    const transition = transitionViewportInteraction(selection.value, {
+      type: 'move',
+      pointerId: event.pointerId,
+      position: { currentX, currentY },
+    })
+    if (!transition.accepted || !transition.state) return
+    const next = transition.state
     selection.value = next
     if (next.kind === 'pan') applyPan(next, track)
     event.preventDefault()
@@ -242,11 +259,7 @@ export function useWaveformViewport(context: ViewportContext) {
   const cancelViewportDrag = (event?: PointerEvent) => {
     const active = selection.value
     if (!active || (event && event.pointerId !== active.pointerId)) return
-    activeOverlay.value?.releasePointerCapture?.(active.pointerId)
-    if (viewportInteraction.value.cancel(event?.pointerId)) {
-      activeOverlay.value = undefined
-      syncSelection()
-    }
+    cleanupViewportDrag(active.pointerId, event)
   }
   const applyBoxZoom = (active: ViewportSelectionState) => {
     const track = trackLayouts.value.find((item) => item.index === active.trackIndex)
@@ -314,9 +327,11 @@ export function useWaveformViewport(context: ViewportContext) {
     const active = selection.value
     if (!active || event.pointerId !== active.pointerId) return
     const track = trackLayouts.value.find((item) => item.index === active.trackIndex)
-    if (!track) return
     const overlay = activeOverlay.value
-    if (!overlay) return
+    if (!track || !overlay || !overlay.parentNode) {
+      cleanupViewportDrag(active.pointerId, event)
+      return
+    }
     const [rawX, rawY] = pointer(event, overlay)
     const currentX = Math.max(
       0,
@@ -326,11 +341,15 @@ export function useWaveformViewport(context: ViewportContext) {
       0,
       Math.min(active.independent ? track.height : innerHeight.value, rawY),
     )
-    const completed = viewportInteraction.value.finish(event.pointerId, { currentX, currentY })
+    const completed = transitionViewportInteraction(selection.value, {
+      type: 'finish',
+      pointerId: event.pointerId,
+      position: { currentX, currentY },
+    }).completed
     if (!completed) return
-    overlay.releasePointerCapture?.(completed.pointerId)
+    selection.value = null
+    releasePointerCapture(completed.pointerId, event)
     activeOverlay.value = undefined
-    syncSelection()
     event.preventDefault()
     if (completed.kind === 'pan') {
       applyPan(completed, track)
@@ -367,7 +386,6 @@ export function useWaveformViewport(context: ViewportContext) {
     resetViewport()
     emit('zoom-reset')
   }
-
   return {
     selectionBox,
     beginViewportDrag,
diff --git a/src/components/interaction/viewportInteractionState.test.ts b/src/components/interaction/viewportInteractionState.test.ts
index 36fdccb..36eb3c6 100644
--- a/src/components/interaction/viewportInteractionState.test.ts
+++ b/src/components/interaction/viewportInteractionState.test.ts
@@ -1,6 +1,10 @@
 import { describe, expect, it } from 'vitest'
 
-import { ViewportInteractionStateMachine } from './viewportInteractionState'
+import {
+  reduceViewportInteraction,
+  transitionViewportInteraction,
+  type ViewportInteractionEvent,
+} from './viewportInteractionState'
 
 const gesture = {
   trackIndex: 2,
@@ -13,64 +17,85 @@ const gesture = {
   yDomains: { track: [-1, 1] as [number, number] },
 }
 
-describe('ViewportInteractionStateMachine', () => {
-  it('accepts one gesture and rejects a conflicting start', () => {
-    const machine = new ViewportInteractionStateMachine()
-
-    expect(machine.begin(gesture)).toBe(true)
-    expect(machine.begin({ ...gesture, pointerId: 8 })).toBe(false)
-    expect(machine.state).toMatchObject({ kind: 'box', pointerId: 7 })
-  })
-
-  it('rejects moves and completion from a different pointer', () => {
-    const machine = new ViewportInteractionStateMachine()
-    machine.begin(gesture)
-
-    expect(machine.move(8, { currentX: 30, currentY: 40 })).toBeNull()
-    expect(machine.finish(8, { currentX: 30, currentY: 40 })).toBeNull()
-    expect(machine.state?.currentX).toBe(10)
-  })
-
-  it('updates a valid pointer, completes it, and returns to idle', () => {
-    const machine = new ViewportInteractionStateMachine()
-    machine.begin({ ...gesture, kind: 'pan' })
-
-    expect(machine.move(7, { currentX: 30, currentY: 40 })).toMatchObject({
-      kind: 'pan',
-      currentX: 30,
-      currentY: 40,
+describe('viewport interaction reducer', () => {
+  it('accepts one begin and rejects a conflicting begin', () => {
+    const started = transitionViewportInteraction(null, { type: 'begin', gesture })
+    const conflicting = transitionViewportInteraction(started.state, {
+      type: 'begin',
+      gesture: { ...gesture, pointerId: 8 },
     })
-    expect(machine.finish(7, { currentX: 50, currentY: 60 })).toMatchObject({
-      kind: 'pan',
-      currentX: 50,
-      currentY: 60,
+
+    expect(started.accepted).toBe(true)
+    expect(started.state).toMatchObject({ kind: 'box', pointerId: 7 })
+    expect(conflicting.accepted).toBe(false)
+    expect(conflicting.state).toMatchObject({ kind: 'box', pointerId: 7 })
+  })
+
+  it('rejects move and finish from a different pointer without changing state', () => {
+    const state = reduceViewportInteraction(null, { type: 'begin', gesture })
+    const move = transitionViewportInteraction(state, {
+      type: 'move',
+      pointerId: 8,
+      position: { currentX: 30, currentY: 40 },
     })
-    expect(machine.state).toBeNull()
+    const finish = transitionViewportInteraction(move.state, {
+      type: 'finish',
+      pointerId: 8,
+      position: { currentX: 30, currentY: 40 },
+    })
+
+    expect(move.accepted).toBe(false)
+    expect(finish.accepted).toBe(false)
+    expect(finish.state).toMatchObject({ currentX: 10, currentY: 20 })
   })
 
-  it('only cancels the owning pointer and supports explicit reset', () => {
-    const machine = new ViewportInteractionStateMachine()
-    machine.begin(gesture)
+  it('updates a valid pointer and returns the completed snapshot on finish', () => {
+    const state = reduceViewportInteraction(null, {
+      type: 'begin',
+      gesture: { ...gesture, kind: 'pan' },
+    })
+    const moved = transitionViewportInteraction(state, {
+      type: 'move',
+      pointerId: 7,
+      position: { currentX: 30, currentY: 40 },
+    })
+    const finished = transitionViewportInteraction(moved.state, {
+      type: 'finish',
+      pointerId: 7,
+      position: { currentX: 50, currentY: 60 },
+    })
 
-    expect(machine.cancel(8)).toBe(false)
-    expect(machine.state).not.toBeNull()
-    expect(machine.cancel(7)).toBe(true)
-    expect(machine.state).toBeNull()
-
-    machine.begin(gesture)
-    machine.reset()
-    expect(machine.state).toBeNull()
+    expect(moved.state).toMatchObject({ kind: 'pan', currentX: 30, currentY: 40 })
+    expect(finished.completed).toMatchObject({ kind: 'pan', currentX: 50, currentY: 60 })
+    expect(finished.state).toBeNull()
   })
 
-  it('returns defensive copies from its state getter', () => {
-    const machine = new ViewportInteractionStateMachine()
-    machine.begin(gesture)
-    const snapshot = machine.state!
-    snapshot.currentX = 99
-    snapshot.xDomain[0] = 50
-    snapshot.yDomains.track![0] = 50
+  it('cancels only the owning pointer and supports cancel/reset events', () => {
+    const state = reduceViewportInteraction(null, { type: 'begin', gesture })
+    const rejectedCancel = transitionViewportInteraction(state, { type: 'cancel', pointerId: 8 })
+    const cancelled = transitionViewportInteraction(rejectedCancel.state, {
+      type: 'cancel',
+      pointerId: 7,
+    })
+    const restarted = reduceViewportInteraction(null, { type: 'begin', gesture })
+    const reset = transitionViewportInteraction(restarted, { type: 'reset' })
 
-    expect(machine.state).toMatchObject({ currentX: 10, xDomain: [0, 100] })
-    expect(machine.state?.yDomains.track).toEqual([-1, 1])
+    expect(rejectedCancel.accepted).toBe(false)
+    expect(rejectedCancel.state).not.toBeNull()
+    expect(cancelled.accepted).toBe(true)
+    expect(cancelled.state).toBeNull()
+    expect(reset.accepted).toBe(true)
+    expect(reset.state).toBeNull()
+  })
+
+  it('keeps events discriminated and does not mutate the begin input', () => {
+    const event: ViewportInteractionEvent = { type: 'begin', gesture }
+    const state = reduceViewportInteraction(null, event)
+
+    expect(state).not.toBeNull()
+    expect(state?.xDomain).toEqual([0, 100])
+    expect(state?.yDomains.track).toEqual([-1, 1])
+    expect(event.gesture.xDomain).toEqual([0, 100])
+    expect(event.gesture.yDomains.track).toEqual([-1, 1])
   })
 })
diff --git a/src/components/interaction/viewportInteractionState.ts b/src/components/interaction/viewportInteractionState.ts
index e7ba1cd..4ef64de 100644
--- a/src/components/interaction/viewportInteractionState.ts
+++ b/src/components/interaction/viewportInteractionState.ts
@@ -16,65 +16,74 @@ export interface ViewportGesturePosition {
   currentY: number
 }
 
-function cloneState(state: ViewportSelectionState | null): ViewportSelectionState | null {
-  if (!state) return null
+export type ViewportInteractionEvent =
+  | { type: 'begin'; gesture: ViewportGestureStart }
+  | { type: 'move'; pointerId: number; position: ViewportGesturePosition }
+  | { type: 'finish'; pointerId: number; position: ViewportGesturePosition }
+  | { type: 'cancel'; pointerId?: number }
+  | { type: 'reset' }
+
+export interface ViewportInteractionTransition {
+  state: ViewportSelectionState | null
+  accepted: boolean
+  completed: ViewportSelectionState | null
+}
+
+function createSelectionState(input: ViewportGestureStart): ViewportSelectionState {
   return {
-    ...state,
-    xDomain: [...state.xDomain],
+    ...input,
+    currentX: input.startX,
+    currentY: input.startY,
+    xDomain: [...input.xDomain],
     yDomains: Object.fromEntries(
-      Object.entries(state.yDomains).map(([key, domain]) => [key, [...domain] as [number, number]]),
+      Object.entries(input.yDomains).map(([key, domain]) => [key, [...domain] as [number, number]]),
     ),
   }
 }
 
-/** Owns the legal lifecycle of one active viewport pointer gesture. */
-export class ViewportInteractionStateMachine {
-  private current: ViewportSelectionState | null = null
+function withPosition(
+  state: ViewportSelectionState,
+  position: ViewportGesturePosition,
+): ViewportSelectionState {
+  return { ...state, ...position }
+}
 
-  get state(): ViewportSelectionState | null {
-    return cloneState(this.current)
-  }
+function rejectedTransition(state: ViewportSelectionState | null): ViewportInteractionTransition {
+  return { state, accepted: false, completed: null }
+}
 
-  begin(input: ViewportGestureStart): boolean {
-    if (this.current) return false
-    this.current = {
-      ...input,
-      currentX: input.startX,
-      currentY: input.startY,
-      xDomain: [...input.xDomain],
-      yDomains: Object.fromEntries(
-        Object.entries(input.yDomains).map(([key, domain]) => [
-          key,
-          [...domain] as [number, number],
-        ]),
-      ),
-    }
-    return true
-  }
-
-  move(pointerId: number, position: ViewportGesturePosition): ViewportSelectionState | null {
-    if (!this.current || this.current.pointerId !== pointerId) return null
-    this.current = { ...this.current, ...position }
-    return this.state
-  }
-
-  finish(pointerId: number, position: ViewportGesturePosition): ViewportSelectionState | null {
-    if (!this.current || this.current.pointerId !== pointerId) return null
-    this.current = { ...this.current, ...position }
-    const completed = this.state
-    this.current = null
-    return completed
-  }
-
-  cancel(pointerId?: number): boolean {
-    if (!this.current || (pointerId !== undefined && this.current.pointerId !== pointerId)) {
-      return false
-    }
-    this.current = null
-    return true
-  }
-
-  reset(): void {
-    this.current = null
+export function transitionViewportInteraction(
+  state: ViewportSelectionState | null,
+  event: ViewportInteractionEvent,
+): ViewportInteractionTransition {
+  switch (event.type) {
+    case 'begin':
+      return state
+        ? rejectedTransition(state)
+        : { state: createSelectionState(event.gesture), accepted: true, completed: null }
+    case 'move':
+      if (!state || state.pointerId !== event.pointerId) return rejectedTransition(state)
+      return { state: withPosition(state, event.position), accepted: true, completed: null }
+    case 'finish':
+      if (!state || state.pointerId !== event.pointerId) return rejectedTransition(state)
+      return {
+        state: null,
+        accepted: true,
+        completed: withPosition(state, event.position),
+      }
+    case 'cancel':
+      if (!state || (event.pointerId !== undefined && state.pointerId !== event.pointerId)) {
+        return rejectedTransition(state)
+      }
+      return { state: null, accepted: true, completed: null }
+    case 'reset':
+      return { state: null, accepted: true, completed: null }
   }
 }
+
+export function reduceViewportInteraction(
+  state: ViewportSelectionState | null,
+  event: ViewportInteractionEvent,
+): ViewportSelectionState | null {
+  return transitionViewportInteraction(state, event).state
+}
diff --git a/src/components/waveformChartCases/viewportLifecycle.test.ts b/src/components/waveformChartCases/viewportLifecycle.test.ts
new file mode 100644
index 0000000..1abd5fc
--- /dev/null
+++ b/src/components/waveformChartCases/viewportLifecycle.test.ts
@@ -0,0 +1,132 @@
+import { flushPromises } from '@vue/test-utils'
+import { describe, expect, it, vi } from 'vitest'
+
+import { gridSeries, mountSizedChart } from '../../test/waveformChart'
+import WaveformChartView from '../WaveformChartView.vue'
+
+describe('WaveformChart viewport lifecycle', () => {
+  it('cleans an active shared gesture when its track is removed', async () => {
+    const wrapper = await mountSizedChart(gridSeries(2), {
+      displayMode: 'separated',
+      grid: { rowCount: 2, columnCount: 1 },
+    })
+    const overlay = wrapper.get('.waveform-chart__overlay--shared')
+    const width = Number(overlay.attributes('width'))
+    const height = Number(overlay.attributes('height'))
+    const releasePointerCapture = vi.fn()
+    Object.defineProperty(overlay.element, 'getBoundingClientRect', {
+      value: () => ({ left: 0, top: 0, width, height }),
+    })
+    Object.defineProperty(overlay.element, 'setPointerCapture', { value: vi.fn() })
+    Object.defineProperty(overlay.element, 'releasePointerCapture', {
+      value: releasePointerCapture,
+    })
+
+    const dispatchPointer = (type: string, pointerId: number, clientY: number) => {
+      const event = new MouseEvent(type, {
+        button: 0,
+        clientX: width / 2,
+        clientY,
+        bubbles: true,
+      })
+      Object.defineProperty(event, 'pointerId', { value: pointerId })
+      overlay.element.dispatchEvent(event)
+    }
+
+    dispatchPointer('pointerdown', 41, height * 0.75)
+    await flushPromises()
+    expect(wrapper.find('.waveform-chart__zoom-selection').exists()).toBe(true)
+
+    await wrapper.setProps({ data: gridSeries(1) })
+    await flushPromises()
+    dispatchPointer('pointerup', 41, height * 0.75)
+    await flushPromises()
+
+    expect(releasePointerCapture).toHaveBeenCalledWith(41)
+    expect(wrapper.find('.waveform-chart__zoom-selection').exists()).toBe(false)
+
+    dispatchPointer('pointerdown', 42, height / 2)
+    dispatchPointer('pointermove', 42, height / 2 + 20)
+    await flushPromises()
+    expect(wrapper.find('.waveform-chart__zoom-selection').exists()).toBe(true)
+  })
+
+  it('cleans an active gesture when its overlay leaves the DOM', async () => {
+    const wrapper = await mountSizedChart(
+      {
+        kind: 'points',
+        points: [
+          { x: 0, y: 0 },
+          { x: 1, y: 1 },
+        ],
+      },
+      { displayMode: 'separated' },
+    )
+    const overlay = wrapper.get('.waveform-chart__overlay--shared')
+    const width = Number(overlay.attributes('width'))
+    const height = Number(overlay.attributes('height'))
+    const releasePointerCapture = vi.fn(() => {
+      throw new DOMException('Pointer capture is no longer available', 'NotFoundError')
+    })
+    Object.defineProperty(overlay.element, 'getBoundingClientRect', {
+      value: () => ({ left: 0, top: 0, width, height }),
+    })
+    Object.defineProperty(overlay.element, 'setPointerCapture', { value: vi.fn() })
+    Object.defineProperty(overlay.element, 'releasePointerCapture', {
+      value: releasePointerCapture,
+    })
+
+    const down = new MouseEvent('pointerdown', {
+      button: 0,
+      clientX: width / 2,
+      clientY: height / 2,
+      bubbles: true,
+    })
+    Object.defineProperty(down, 'pointerId', { value: 43 })
+    overlay.element.dispatchEvent(down)
+    await wrapper.setProps({ hiddenSeriesIds: ['series-0'] })
+    await flushPromises()
+
+    expect(wrapper.find('.waveform-chart__overlay--shared').exists()).toBe(false)
+    const view = wrapper.findComponent(WaveformChartView)
+    const finishViewportDrag = (
+      view.vm as unknown as { finishViewportDrag: (event: PointerEvent) => void }
+    ).finishViewportDrag
+    const up = new MouseEvent('pointerup', {
+      clientX: width / 2,
+      clientY: height / 2,
+      bubbles: true,
+    })
+    Object.defineProperty(up, 'pointerId', { value: 43 })
+    finishViewportDrag(up as unknown as PointerEvent)
+    await flushPromises()
+
+    expect(releasePointerCapture).toHaveBeenCalledWith(43)
+    expect(wrapper.find('.waveform-chart__zoom-selection').exists()).toBe(false)
+
+    await wrapper.setProps({ hiddenSeriesIds: [] })
+    await flushPromises()
+    const nextOverlay = wrapper.get('.waveform-chart__overlay--shared')
+    Object.defineProperty(nextOverlay.element, 'getBoundingClientRect', {
+      value: () => ({ left: 0, top: 0, width, height }),
+    })
+    const nextDown = new MouseEvent('pointerdown', {
+      button: 0,
+      clientX: width / 2,
+      clientY: height / 2,
+      bubbles: true,
+    })
+    Object.defineProperty(nextDown, 'pointerId', { value: 44 })
+    nextOverlay.element.dispatchEvent(nextDown)
+    const nextMove = new MouseEvent('pointermove', {
+      clientX: width * 0.75,
+      clientY: height / 2,
+      bubbles: true,
+    })
+    Object.defineProperty(nextMove, 'pointerId', { value: 44 })
+    nextOverlay.element.dispatchEvent(nextMove)
+    await flushPromises()
+
+    expect(wrapper.find('.waveform-chart__zoom-selection').exists()).toBe(true)
+  })
+})
diff --git a/src/core/rendering.ts b/src/core/rendering.ts
index bb323ff..759304a 100644
--- a/src/core/rendering.ts
+++ b/src/core/rendering.ts
@@ -75,7 +75,7 @@ function selectRenderablePointsInRange(
   const end = Math.min(points.length, range.end + 1)
   const visibleCount = end - start
   if (visibleCount <= 0) return []
-  return resolveRenderablePointSelectionStrategy({ visibleCount, width, options }).select({
+  return resolveRenderablePointSelectionStrategy({ visibleCount, width, options })({
     points,
     range,
     domain,
diff --git a/src/core/renderingStrategies.test.ts b/src/core/renderingStrategies.test.ts
index 933cd3d..e3a4199 100644
--- a/src/core/renderingStrategies.test.ts
+++ b/src/core/renderingStrategies.test.ts
@@ -3,9 +3,9 @@ import { describe, expect, it } from 'vitest'
 import type { WaveformPoint } from '../types'
 import { DEFAULT_WAVEFORM_RENDERING_OPTIONS } from './renderingOptions'
 import {
-  CompletePointSelectionStrategy,
-  PeakPreservingPointSelectionStrategy,
+  peakPreservingPointSelectionStrategy,
   resolveRenderablePointSelectionStrategy,
+  type RenderablePointSelectionContext,
 } from './renderingStrategies'
 
 const denseOptions = {
@@ -16,42 +16,55 @@ const denseOptions = {
 
 describe('renderable point selection strategies', () => {
   it('resolves complete-point selection at the configured boundaries', () => {
+    const context: RenderablePointSelectionContext = {
+      points: [
+        { x: 0, y: 5 },
+        { x: 1, y: 1 },
+        { x: 2, y: 10 },
+        { x: 3, y: 3 },
+        { x: 4, y: 7 },
+      ],
+      range: { start: 0, end: 5 },
+      domain: [0, 4],
+      width: 100,
+      options: DEFAULT_WAVEFORM_RENDERING_OPTIONS,
+    }
     const complete = resolveRenderablePointSelectionStrategy({
       visibleCount: 100,
       width: 100,
       options: DEFAULT_WAVEFORM_RENDERING_OPTIONS,
-    })
+    })(context)
     const disabled = resolveRenderablePointSelectionStrategy({
       visibleCount: 10_000,
       width: 100,
       options: { ...denseOptions, downsample: false },
-    })
+    })(context)
 
-    expect(complete).toBeInstanceOf(CompletePointSelectionStrategy)
-    expect(disabled).toBeInstanceOf(CompletePointSelectionStrategy)
+    expect(complete).toEqual(context.points)
+    expect(disabled).toEqual(context.points)
   })
 
   it('resolves peak-preserving selection for dense visible data', () => {
-    const strategy = resolveRenderablePointSelectionStrategy({
-      visibleCount: 1_000,
-      width: 100,
+    const context: RenderablePointSelectionContext = {
+      points: [
+        { x: 0, y: 5 },
+        { x: 1, y: 1 },
+        { x: 2, y: 10 },
+        { x: 3, y: 3 },
+        { x: 4, y: 7 },
+      ],
+      range: { start: 0, end: 5 },
+      domain: [0, 4],
+      width: 4,
       options: denseOptions,
-    })
+    }
+    const selected = resolveRenderablePointSelectionStrategy({
+      visibleCount: 1_000,
+      width: 4,
+      options: denseOptions,
+    })(context)
 
-    expect(strategy).toBeInstanceOf(PeakPreservingPointSelectionStrategy)
-    expect(strategy.name).toBe('peak-preserving')
-  })
-
-  it('reuses the resolved strategy instance across selections', () => {
-    const request = { visibleCount: 100, width: 100, options: DEFAULT_WAVEFORM_RENDERING_OPTIONS }
-    const peakRequest = { visibleCount: 1_000, width: 100, options: denseOptions }
-
-    expect(resolveRenderablePointSelectionStrategy(request)).toBe(
-      resolveRenderablePointSelectionStrategy(request),
-    )
-    expect(resolveRenderablePointSelectionStrategy(peakRequest)).toBe(
-      resolveRenderablePointSelectionStrategy(peakRequest),
-    )
+    expect(selected).toEqual(expect.arrayContaining([context.points[1], context.points[2]]))
   })
 
   it('retains first, last, minimum, and maximum points in a peak bucket', () => {
@@ -62,8 +75,7 @@ describe('renderable point selection strategies', () => {
       { x: 3, y: 3 },
       { x: 4, y: 7 },
     ]
-    const strategy = new PeakPreservingPointSelectionStrategy()
-    const selected = strategy.select({
+    const selected = peakPreservingPointSelectionStrategy({
       points,
       range: { start: 0, end: points.length },
       domain: [0, 4],
diff --git a/src/core/renderingStrategies.ts b/src/core/renderingStrategies.ts
index 7e71ee1..e233905 100644
--- a/src/core/renderingStrategies.ts
+++ b/src/core/renderingStrategies.ts
@@ -14,10 +14,9 @@ export interface RenderablePointSelectionContext {
   options: ResolvedWaveformRenderingOptions
 }
 
-export interface RenderablePointSelectionStrategy {
-  readonly name: 'complete' | 'peak-preserving'
-  select(context: RenderablePointSelectionContext): WaveformPoint[]
-}
+export type RenderablePointSelectionStrategy = (
+  context: RenderablePointSelectionContext,
+) => WaveformPoint[]
 
 function selectionBounds(range: VisiblePointRange, pointCount: number) {
   return {
@@ -30,91 +29,83 @@ function pushUniquePoint(target: WaveformPoint[], point: WaveformPoint | undefin
   if (point && target[target.length - 1] !== point) target.push(point)
 }
 
-export class CompletePointSelectionStrategy implements RenderablePointSelectionStrategy {
-  readonly name = 'complete' as const
-
-  select(context: RenderablePointSelectionContext): WaveformPoint[] {
-    const { start, end } = selectionBounds(context.range, context.points.length)
-    return context.points.slice(start, end)
-  }
+export const completePointSelectionStrategy: RenderablePointSelectionStrategy = (context) => {
+  const { start, end } = selectionBounds(context.range, context.points.length)
+  return context.points.slice(start, end)
 }
 
-export class PeakPreservingPointSelectionStrategy implements RenderablePointSelectionStrategy {
-  readonly name = 'peak-preserving' as const
+export const peakPreservingPointSelectionStrategy: RenderablePointSelectionStrategy = (context) => {
+  const { points, range, domain, width, options } = context
+  const { start, end } = selectionBounds(range, points.length)
+  const visibleCount = end - start
+  if (visibleCount <= 0) return []
 
-  select(context: RenderablePointSelectionContext): WaveformPoint[] {
-    const { points, range, domain, width, options } = context
-    const { start, end } = selectionBounds(range, points.length)
-    const visibleCount = end - start
-    if (visibleCount <= 0) return []
+  const domainStart = Math.min(domain[0], domain[1])
+  const domainEnd = Math.max(domain[0], domain[1])
+  const maximumPointCount = Math.max(4, Math.floor(width * options.maxPointsPerPixel))
+  const bucketCount = Math.max(1, Math.floor(maximumPointCount / 4))
+  const result: WaveformPoint[] = []
+  const span = domainEnd - domainStart || 1
+  const bucketIndexes = Array.from({ length: 4 }, () => -1)
+  let activeBucket = -1
+  let firstIndex = -1
+  let lastIndex = -1
+  let minimumIndex = -1
+  let maximumIndex = -1
 
-    const domainStart = Math.min(domain[0], domain[1])
-    const domainEnd = Math.max(domain[0], domain[1])
-    const maximumPointCount = Math.max(4, Math.floor(width * options.maxPointsPerPixel))
-    const bucketCount = Math.max(1, Math.floor(maximumPointCount / 4))
-    const result: WaveformPoint[] = []
-    const span = domainEnd - domainStart || 1
-    const bucketIndexes = Array.from({ length: 4 }, () => -1)
-    let activeBucket = -1
-    let firstIndex = -1
-    let lastIndex = -1
-    let minimumIndex = -1
-    let maximumIndex = -1
-
-    const addBucketIndex = (index: number, count: number) => {
-      if (index < 0) return count
-      for (let position = 0; position < count; position += 1) {
-        if (bucketIndexes[position] === index) return count
-      }
-      bucketIndexes[count] = index
-      return count + 1
+  const addBucketIndex = (index: number, count: number) => {
+    if (index < 0) return count
+    for (let position = 0; position < count; position += 1) {
+      if (bucketIndexes[position] === index) return count
     }
-
-    const flushBucket = () => {
-      if (firstIndex < 0) return
-      let count = 0
-      count = addBucketIndex(firstIndex, count)
-      count = addBucketIndex(minimumIndex, count)
-      count = addBucketIndex(maximumIndex, count)
-      count = addBucketIndex(lastIndex, count)
-      for (let index = 1; index < count; index += 1) {
-        const value = bucketIndexes[index]
-        let position = index - 1
-        while (position >= 0 && bucketIndexes[position] > value) {
-          bucketIndexes[position + 1] = bucketIndexes[position]
-          position -= 1
-        }
-        bucketIndexes[position + 1] = value
-      }
-      for (let index = 0; index < count; index += 1) {
-        pushUniquePoint(result, points[bucketIndexes[index]])
-      }
-    }
-
-    pushUniquePoint(result, points[start])
-    for (let index = range.start; index < range.end; index += 1) {
-      const point = points[index]
-      const bucket = Math.min(
-        bucketCount - 1,
-        Math.max(0, Math.floor(((point.x - domainStart) / span) * bucketCount)),
-      )
-      if (bucket !== activeBucket) {
-        flushBucket()
-        activeBucket = bucket
-        firstIndex = index
-        lastIndex = index
-        minimumIndex = index
-        maximumIndex = index
-        continue
-      }
-      lastIndex = index
-      if (point.y < points[minimumIndex].y) minimumIndex = index
-      if (point.y > points[maximumIndex].y) maximumIndex = index
-    }
-    flushBucket()
-    pushUniquePoint(result, points[end - 1])
-    return result
+    bucketIndexes[count] = index
+    return count + 1
   }
+
+  const flushBucket = () => {
+    if (firstIndex < 0) return
+    let count = 0
+    count = addBucketIndex(firstIndex, count)
+    count = addBucketIndex(minimumIndex, count)
+    count = addBucketIndex(maximumIndex, count)
+    count = addBucketIndex(lastIndex, count)
+    for (let index = 1; index < count; index += 1) {
+      const value = bucketIndexes[index]
+      let position = index - 1
+      while (position >= 0 && bucketIndexes[position] > value) {
+        bucketIndexes[position + 1] = bucketIndexes[position]
+        position -= 1
+      }
+      bucketIndexes[position + 1] = value
+    }
+    for (let index = 0; index < count; index += 1) {
+      pushUniquePoint(result, points[bucketIndexes[index]])
+    }
+  }
+
+  pushUniquePoint(result, points[start])
+  for (let index = range.start; index < range.end; index += 1) {
+    const point = points[index]
+    const bucket = Math.min(
+      bucketCount - 1,
+      Math.max(0, Math.floor(((point.x - domainStart) / span) * bucketCount)),
+    )
+    if (bucket !== activeBucket) {
+      flushBucket()
+      activeBucket = bucket
+      firstIndex = index
+      lastIndex = index
+      minimumIndex = index
+      maximumIndex = index
+      continue
+    }
+    lastIndex = index
+    if (point.y < points[minimumIndex].y) minimumIndex = index
+    if (point.y > points[maximumIndex].y) maximumIndex = index
+  }
+  flushBucket()
+  pushUniquePoint(result, points[end - 1])
+  return result
 }
 
 export interface RenderablePointSelectionStrategyRequest {
@@ -123,27 +114,18 @@ export interface RenderablePointSelectionStrategyRequest {
   options: ResolvedWaveformRenderingOptions
 }
 
-export class RenderablePointSelectionStrategyFactory {
-  private readonly complete = new CompletePointSelectionStrategy()
-  private readonly peakPreserving = new PeakPreservingPointSelectionStrategy()
-
-  resolve(request: RenderablePointSelectionStrategyRequest): RenderablePointSelectionStrategy {
-    const maximumPointCount = Math.max(
-      4,
-      Math.floor(request.width * request.options.maxPointsPerPixel),
-    )
-    const shouldUseCompletePoints =
-      !request.options.downsample ||
-      request.visibleCount <= request.options.downsampleThreshold ||
-      request.visibleCount <= maximumPointCount
-    return shouldUseCompletePoints ? this.complete : this.peakPreserving
-  }
-}
-
-const defaultRenderablePointSelectionStrategyFactory = new RenderablePointSelectionStrategyFactory()
-
 export function resolveRenderablePointSelectionStrategy(
   request: RenderablePointSelectionStrategyRequest,
 ): RenderablePointSelectionStrategy {
-  return defaultRenderablePointSelectionStrategyFactory.resolve(request)
+  const maximumPointCount = Math.max(
+    4,
+    Math.floor(request.width * request.options.maxPointsPerPixel),
+  )
+  const shouldUseCompletePoints =
+    !request.options.downsample ||
+    request.visibleCount <= request.options.downsampleThreshold ||
+    request.visibleCount <= maximumPointCount
+  return shouldUseCompletePoints
+    ? completePointSelectionStrategy
+    : peakPreservingPointSelectionStrategy
 }
diff --git a/src/data/simulatedWaveforms.ts b/src/data/simulatedWaveforms.ts
index bd406bd..0823b44 100644
--- a/src/data/simulatedWaveforms.ts
+++ b/src/data/simulatedWaveforms.ts
@@ -6,16 +6,15 @@ const END_TIME = 5
 const TWO_PI = Math.PI * 2
 
 type SignalGenerator = (time: number, noise: number) => number
-type ErrorGenerator = (time: number, value: number) => Pick<
-  WaveformPoint,
-  'error' | 'lowerError' | 'upperError'
->
+type ErrorGenerator = (
+  time: number,
+  value: number,
+) => Pick<WaveformPoint, 'error' | 'lowerError' | 'upperError'>
 
-interface SimulatedSeriesDefinition
-  extends Pick<
-    WaveformSeries,
-    'id' | 'name' | 'unit' | 'lineType' | 'pointType' | 'errorBar'
-  > {
+interface SimulatedSeriesDefinition extends Pick<
+  WaveformSeries,
+  'id' | 'name' | 'unit' | 'lineType' | 'pointType' | 'errorBar'
+> {
   signal: SignalGenerator
   errors?: ErrorGenerator
 }
@@ -39,7 +38,7 @@ function createPoints(
     return {
       x: time,
       y: value,
-      ...(errors?.(time, value) ?? {}),
+      ...errors?.(time, value),
     }
   })
 }
diff --git a/src/utils/formatters.test.ts b/src/utils/formatters.test.ts
index d2a234d..96540cb 100644
--- a/src/utils/formatters.test.ts
+++ b/src/utils/formatters.test.ts
@@ -40,10 +40,11 @@ describe('waveform number formatters', () => {
     expect(formatScientificAxisExponent(0.0001, 0.0003)).toBe('E-04')
   })
 
-  it('derives the exponent from Math.max(axisMin, axisMax)', () => {
+  it('derives the exponent from the largest absolute endpoint', () => {
     expect(resolveScientificAxisExponent(-9000, -1000)).toBe(3)
-    expect(resolveScientificAxisExponent(-10_000, 3000)).toBe(3)
-    expect(resolveScientificAxisExponent(-1000, 0)).toBeNull()
+    expect(resolveScientificAxisExponent(-100_000, -3000)).toBe(5)
+    expect(resolveScientificAxisExponent(-10_000, 3000)).toBe(4)
+    expect(resolveScientificAxisExponent(-1000, 0)).toBe(3)
     expect(resolveScientificAxisExponent(0, 0)).toBeNull()
   })
 
diff --git a/src/utils/formatters.ts b/src/utils/formatters.ts
index 076aff9..ef638ee 100644
--- a/src/utils/formatters.ts
+++ b/src/utils/formatters.ts
@@ -42,8 +42,7 @@ export function shouldUseScientificAxisLabel(maxAbsoluteValue: number): boolean
 export function resolveScientificAxisExponent(axisMin?: number, axisMax?: number): number | null {
   if (typeof axisMin !== 'number' || typeof axisMax !== 'number') return null
 
-  const maxValue = Math.max(axisMin, axisMax)
-  const absoluteMaxValue = Math.abs(maxValue)
+  const absoluteMaxValue = Math.max(Math.abs(axisMin), Math.abs(axisMax))
   return shouldUseScientificAxisLabel(absoluteMaxValue)
     ? Math.floor(Math.log10(absoluteMaxValue))
     : null
diff --git a/src/utils/sampling.ts b/src/utils/sampling.ts
index 51dd808..35ec295 100644
--- a/src/utils/sampling.ts
+++ b/src/utils/sampling.ts
@@ -37,7 +37,8 @@ export function downsampleLTTB(data: WaveformPoint[], threshold: number): Wavefo
 
   // 确保阈值至少为 3
   const sampledLength = Math.max(3, Math.floor(threshold))
-  const sampled: WaveformPoint[] = new Array(sampledLength)
+  const sampled: WaveformPoint[] = []
+  sampled.length = sampledLength
 
   // 始终保留第一个和最后一个点
   sampled[0] = data[0]!