diff --git a/package.json b/package.json
index bcaa94766fe..e5bf821656f 100644
--- a/package.json
+++ b/package.json
@@ -237,7 +237,6 @@
     "@sanity/diff-match-patch": "^3.2.1",
     "@shadcn/lint": "~0.1.5",
     "@stablyai/playwright-test": "^2.1.16",
-    "@streamparser/json": "0.0.26",
     "@tailwindcss/vite": "^4.3.3",
     "@tanstack/react-virtual": "^3.14.13",
     "@testing-library/jest-dom": "^6.9.1",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 0511935d489..95c2762ff2e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -313,9 +313,6 @@ importers:
       '@stablyai/playwright-test':
         specifier: ^2.1.16
         version: 2.1.16(@playwright/test@1.63.0(electron@43.7.8(supports-color@7.2.0)))(zod@4.6.7)
-      '@streamparser/json':
-        specifier: 0.0.26
-        version: 0.0.26
       '@tailwindcss/vite':
         specifier: ^4.3.3
         version: 4.3.3(vite@8.3.4(@types/node@24.19.2)(esbuild@0.28.2)(jiti@2.7.0)(tsx@4.23.15)(yaml@2.9.1))
@@ -3164,9 +3161,6 @@ packages:
       '@types/playwright__test':
         optional: true
 
-  '@streamparser/json@0.0.26':
-    resolution: {integrity: sha512-46597LNFI+MFdUnzX2QJWwmdTRdq0XVD+vVNJTtGVzIrnCuhG9pFo1OAzbNBqci8UJgk/X5KJZ6LcV+y7PTuDQ==}
-
   '@swc/core-darwin-arm64@1.16.2':
     resolution: {integrity: sha512-i/j0HNbnn79qnTVPicvay92Nark8fW8NQqn1e2mGERjUXNpBV0+SwQxlRpk2zBhn6laJ8PDI6Kn1nHZhnz3LCA==}
     engines: {node: '>=10'}
@@ -10211,8 +10205,6 @@ snapshots:
       - '@types/zod'
       - zod
 
-  '@streamparser/json@0.0.26': {}
-
   '@swc/core-darwin-arm64@1.16.2':
     optional: true
 
diff --git a/tests/e2e/cross-version-wire/release-checkout.unit.test.ts b/tests/e2e/cross-version-wire/release-checkout.unit.test.ts
index da0d4536416..bcccb903bf5 100644
--- a/tests/e2e/cross-version-wire/release-checkout.unit.test.ts
+++ b/tests/e2e/cross-version-wire/release-checkout.unit.test.ts
@@ -300,47 +300,26 @@ describe('release checkout materialization', () => {
     expect(relative(cacheRoot, checkout.root)).not.toMatch(/^\.\./)
   }, 180_000)
 
-  // Keep @streamparser/json in root devDependencies: v1.4.221's dense parser imports it.
-  // Default cache root: package resolution must walk up into the repo's node_modules.
-  it('runs the released dense parser with its retained test dependency', async () => {
+  // Default cache root lets released source resolve packages from the repo's node_modules.
+  it('runs a released schema with an existing package dependency', async () => {
     const checkout = await materializeReleaseCheckout('v1.4.221')
-    const ripgrep = await importReleaseCheckoutModule(
+    const schema = await importReleaseCheckoutModule(
       checkout,
-      '/src/shared/ripgrep-dense-match-json.ts'
+      '/src/shared/agent-session-context-usage-schema.ts'
     )
-    const callExport = (name: string, ...args: unknown[]): unknown => {
-      const exported = ripgrep[name]
-      if (typeof exported !== 'function') {
-        throw new Error(`v1.4.221 ripgrep-dense-match-json has no ${name} export`)
-      }
-      return exported(...args)
+    const isAdmissible = schema.isAdmissibleAgentSessionContextUsage
+    if (typeof isAdmissible !== 'function') {
+      throw new Error('v1.4.221 has no isAdmissibleAgentSessionContextUsage export')
     }
-    const limits = { structuralTokens: 64, nestingDepth: 8 }
 
-    expect(callExport('parseRipgrepMatchJson', '{"type":"match"}', 1, limits)).toEqual({
-      type: 'match'
-    })
-    expect(callExport('parseDenseRipgrepMatchJson', '{"type":"match"}', 1, 8)).toEqual({
-      type: 'match',
-      data: { submatches: [] }
-    })
-    const match = {
-      type: 'match',
-      data: {
-        path: { text: 'src/example.ts' },
-        lines: { text: 'hit hit\n' },
-        line_number: 7,
-        submatches: [
-          { start: 0, end: 3 },
-          { start: 4, end: 7 }
-        ]
-      }
-    }
-    expect(callExport('parseDenseRipgrepMatchJson', JSON.stringify(match), 1, 8)).toEqual({
-      ...match,
-      data: { ...match.data, submatches: [{ start: 0, end: 3 }] }
-    })
-    expect(() => callExport('parseDenseRipgrepMatchJson', '{"type":', 1, 8)).toThrow()
+    expect(
+      isAdmissible({
+        window: { tokens: 200_000, capturedAt: 1 },
+        used: { kind: 'unknown', capturedAt: 1 }
+      })
+    ).toBe(true)
+    expect(isAdmissible({ window: { tokens: 0, capturedAt: 1 } })).toBe(false)
+    expect(isAdmissible({ used: { kind: 'invalid', capturedAt: 1 } })).toBe(false)
   }, 180_000)
 
   it('keeps an import live while another colliding release label materializes', async () => {