diff --git a/desktop/electron/services/shell.test.ts b/desktop/electron/services/shell.test.ts
index d814fb79..8145c27b 100644
--- a/desktop/electron/services/shell.test.ts
+++ b/desktop/electron/services/shell.test.ts
@@ -1,8 +1,8 @@
 import { describe, expect, it } from 'vitest'
 import { chmodSync, mkdtempSync, mkdirSync, realpathSync, rmSync, writeFileSync } from 'node:fs'
-import { tmpdir } from 'node:os'
+import { homedir, tmpdir } from 'node:os'
 import { join } from 'node:path'
-import { normalizeExternalUrl, normalizeOpenPath, normalizeSystemSettingsUrl } from './shell'
+import { expandTildePath, normalizeExternalUrl, normalizeOpenPath, normalizeSystemSettingsUrl } from './shell'
 
 describe('Electron shell service', () => {
   it('allows only explicit external URL schemes', () => {
@@ -36,6 +36,20 @@ describe('Electron shell service', () => {
     expect(() => normalizeOpenPath('relative/report.md')).toThrow('absolute')
   })
 
+  it('expands tilde paths per platform', () => {
+    expect(expandTildePath('~', 'darwin')).toBe(homedir())
+    expect(expandTildePath('~/reports/a.html', 'linux')).toBe(`${homedir()}/reports/a.html`)
+    expect(expandTildePath('~\\reports\\a.html', 'win32')).toBe(`${homedir()}\\reports\\a.html`)
+    // On POSIX "~\..." is a regular file name; "~user" expansion is unsupported.
+    expect(expandTildePath('~\\reports\\a.html', 'darwin')).toBe('~\\reports\\a.html')
+    expect(expandTildePath('~user/file.md', 'linux')).toBe('~user/file.md')
+    expect(expandTildePath('a/~/b.md', 'linux')).toBe('a/~/b.md')
+  })
+
+  it('expands tilde paths before the absolute-path check in openPath', () => {
+    expect(normalizeOpenPath('~')).toBe(realpathSync(homedir()))
+  })
+
   it('allows only explicit system settings URLs', () => {
     expect(normalizeSystemSettingsUrl('ms-settings:notifications')).toBe('ms-settings:notifications')
     expect(normalizeSystemSettingsUrl('x-apple.systempreferences:com.apple.preference.notifications')).toBe(
diff --git a/desktop/electron/services/shell.ts b/desktop/electron/services/shell.ts
index c4bcb4c8..74c70eae 100644
--- a/desktop/electron/services/shell.ts
+++ b/desktop/electron/services/shell.ts
@@ -1,4 +1,5 @@
 import { realpathSync, statSync } from 'node:fs'
+import { homedir } from 'node:os'
 import path from 'node:path'
 import { fileURLToPath } from 'node:url'
 
@@ -33,8 +34,25 @@ export function normalizeExternalUrl(target: string): string {
   return url.toString()
 }
 
+/**
+ * Expands a leading tilde to the home directory. `~\` is only a tilde path on
+ * Windows — on POSIX the backslash is a valid filename character.
+ */
+export function expandTildePath(target: string, platform: NodeJS.Platform = process.platform): string {
+  if (
+    target === '~' ||
+    target.startsWith('~/') ||
+    (platform === 'win32' && target.startsWith('~\\'))
+  ) {
+    return homedir() + target.slice(1)
+  }
+  return target
+}
+
 export function normalizeOpenPath(target: string): string {
-  const filePath = target.startsWith('file://') ? fileURLToPath(target) : target
+  const filePath = expandTildePath(
+    target.startsWith('file://') ? fileURLToPath(target) : target,
+  )
   if (!path.isAbsolute(filePath)) {
     throw new Error('System file paths must be absolute')
   }
diff --git a/desktop/src/lib/openWithContextForHref.test.ts b/desktop/src/lib/openWithContextForHref.test.ts
index b294c0f6..31099e4f 100644
--- a/desktop/src/lib/openWithContextForHref.test.ts
+++ b/desktop/src/lib/openWithContextForHref.test.ts
@@ -50,6 +50,25 @@ describe('openWithContextForHref', () => {
     const result = openWithContextForHref('src/index.ts', { sessionId: SESSION, serverBaseUrl: BASE, workDir: '/proj/' })
     expect(result).toEqual({ kind: 'file', absolutePath: '/proj/src/index.ts', relPath: 'src/index.ts', previewable: true })
   })
+
+  it('tilde html path → absolutePath passed through, not joined onto workDir', () => {
+    const result = openWithContextForHref('~/reports/a.html', { sessionId: SESSION, serverBaseUrl: BASE, workDir: '/w' })
+    expect(result).toEqual({
+      kind: 'file',
+      absolutePath: '~/reports/a.html',
+      inAppBrowserUrl: previewFsUrl(BASE, SESSION, '~/reports/a.html'),
+    })
+  })
+
+  it('Windows backslash tilde html path → absolutePath passed through', () => {
+    const result = openWithContextForHref('~\\reports\\a.html', { sessionId: SESSION, serverBaseUrl: BASE, workDir: 'C:/w' })
+    expect(result).toMatchObject({ kind: 'file', absolutePath: '~\\reports\\a.html' })
+  })
+
+  it('tilde markdown path → absolutePath passed through in file-preview context', () => {
+    const result = openWithContextForHref('~/notes/a.md', { sessionId: SESSION, serverBaseUrl: BASE, workDir: '/w' })
+    expect(result).toEqual({ kind: 'file', absolutePath: '~/notes/a.md', relPath: '~/notes/a.md', previewable: true })
+  })
 })
 
 describe('openWithContextForWorkspaceFile', () => {
diff --git a/desktop/src/lib/openWithContextForHref.ts b/desktop/src/lib/openWithContextForHref.ts
index 28065b4a..3dce9eeb 100644
--- a/desktop/src/lib/openWithContextForHref.ts
+++ b/desktop/src/lib/openWithContextForHref.ts
@@ -19,6 +19,9 @@ export function openWithContextForWorkspaceFile(
 }
 
 function resolveAbsolute(workDir: string | undefined, p: string): string {
+  // Tilde paths are home-relative, not workspace-relative — pass them through
+  // for the backend (which knows the home dir and platform) to expand.
+  if (p === '~' || p.startsWith('~/') || p.startsWith('~\\')) return p
   if (!workDir || p.startsWith('/') || /^[a-zA-Z]:[\\/]/.test(p)) return p
   return `${workDir.replace(/[\\/]+$/, '')}/${p.replace(/^[/\\]+/, '')}`
 }
diff --git a/src/server/__tests__/open-target-service.test.ts b/src/server/__tests__/open-target-service.test.ts
index 12410eb0..1dec49f7 100644
--- a/src/server/__tests__/open-target-service.test.ts
+++ b/src/server/__tests__/open-target-service.test.ts
@@ -1,7 +1,7 @@
 import { describe, expect, it } from 'bun:test'
 import { mkdtemp, rm, writeFile } from 'node:fs/promises'
 import { join } from 'node:path'
-import { tmpdir } from 'node:os'
+import { homedir, tmpdir } from 'node:os'
 import { createOpenTargetService } from '../services/openTargetService.js'
 
 async function makeDir(prefix = 'cc-haha-open-target-') {
@@ -327,6 +327,42 @@ describe('openTargetService', () => {
     }
   })
 
+  it('expands a tilde path to the home directory before validation', async () => {
+    const { service, launched } = createService('darwin')
+
+    await expect(service.openTarget({ targetId: 'finder', path: '~' }))
+      .resolves.toMatchObject({ ok: true, path: homedir() })
+
+    expect(launched).toEqual([{ command: 'open', args: [homedir()] }])
+  })
+
+  it('reports missing tilde paths with the expanded home path', async () => {
+    const { service } = createService('darwin')
+    const missing = `~/cc-haha-missing-${Date.now()}/report.html`
+
+    const rejection = expect(service.openTarget({ targetId: 'finder', path: missing })).rejects
+    await rejection.toMatchObject({ code: 'OPEN_TARGET_PATH_MISSING' })
+    await rejection.toThrow(join(homedir(), missing.slice(2)))
+  })
+
+  it('expands Windows backslash tilde paths on win32', async () => {
+    const { service } = createService('win32')
+    const missing = `~\\cc-haha-missing-${Date.now()}\\report.html`
+
+    const rejection = expect(service.openTarget({ targetId: 'explorer', path: missing })).rejects
+    await rejection.toMatchObject({ code: 'OPEN_TARGET_PATH_MISSING' })
+    await rejection.toThrow(homedir() + missing.slice(1))
+  })
+
+  it('keeps backslash tilde names untouched on POSIX platforms', async () => {
+    const { service } = createService('darwin')
+
+    // On POSIX "~\..." is a regular (if odd) file name, not a tilde path.
+    const rejection = expect(service.openTarget({ targetId: 'finder', path: '~\\report.html' })).rejects
+    await rejection.toMatchObject({ code: 'OPEN_TARGET_PATH_MISSING' })
+    await rejection.toThrow('~\\report.html')
+  })
+
   it('reports launch failures instead of returning success', async () => {
     const dir = await makeDir()
     const { service } = createService('darwin', {
diff --git a/src/server/services/openTargetService.ts b/src/server/services/openTargetService.ts
index 45f7dd3b..20a17c60 100644
--- a/src/server/services/openTargetService.ts
+++ b/src/server/services/openTargetService.ts
@@ -610,8 +610,29 @@ async function resolveLaunchPlan(
   return null
 }
 
-async function validateOpenPath(targetPath: string): Promise<ResolvedOpenPath> {
-  const resolvedPath = resolve(targetPath)
+/**
+ * Expands a leading tilde to the home directory. Models frequently emit
+ * `~/report.html` (and `~\report.html` on Windows) for generated files;
+ * without expansion those resolve against the server cwd and always miss.
+ * `~\` is only a tilde path on Windows — on POSIX the backslash is a valid
+ * filename character.
+ */
+function expandTildePath(targetPath: string, platform: OpenTargetPlatform): string {
+  if (
+    targetPath === '~' ||
+    targetPath.startsWith('~/') ||
+    (platform === 'win32' && targetPath.startsWith('~\\'))
+  ) {
+    return homedir() + targetPath.slice(1)
+  }
+  return targetPath
+}
+
+async function validateOpenPath(
+  targetPath: string,
+  platform: OpenTargetPlatform,
+): Promise<ResolvedOpenPath> {
+  const resolvedPath = resolve(expandTildePath(targetPath, platform))
   let entry
   try {
     entry = await stat(resolvedPath)
@@ -972,7 +993,7 @@ export function createOpenTargetService(overrides: Partial<Runtime> = {}) {
       )
     }
 
-    const resolvedPath = await validateOpenPath(input.path)
+    const resolvedPath = await validateOpenPath(input.path, runtime.platform)
     const launchPlan = await resolveLaunchPlan(definition, runtime, resolvedPath)
     if (!launchPlan) {
       throw openTargetError(