diff --git a/tests/env-isolation-declarations.test.ts b/tests/env-isolation-declarations.test.ts
new file mode 100644
index 00000000..76b8b886
--- /dev/null
+++ b/tests/env-isolation-declarations.test.ts
@@ -0,0 +1,41 @@
+// Static guard: every PROVIDER_ENV_VARS entry must be CLEARED or REDIRECTED
+// by tests/setup/env-isolation.ts. A data-dir override that is fingerprinted
+// for cache invalidation but not isolated in tests leaks the developer's real
+// sessions into fixture parses — green on CI (no HERMES_HOME), red on a
+// Hermes-shell laptop. The named hole was HERMES_HOME; the class is every
+// sibling override that session-cache already knows about.
+import { describe, expect, it } from 'vitest'
+import { readFileSync } from 'fs'
+import { dirname, join } from 'path'
+import { fileURLToPath } from 'url'
+
+import { PROVIDER_ENV_VARS } from '../src/session-cache.js'
+
+const SETUP_PATH = join(dirname(fileURLToPath(import.meta.url)), 'setup', 'env-isolation.ts')
+
+function extractConstStringArray(source: string, name: string): string[] {
+  const match = source.match(new RegExp(`const ${name} = \\[([\\s\\S]*?)\\] as const`))
+  if (!match) {
+    throw new Error(`tests/setup/env-isolation.ts: const ${name} = [...] as const not found`)
+  }
+  return [...match[1]!.matchAll(/'([A-Z0-9_]+)'/g)].map(m => m[1]!)
+}
+
+describe('env-isolation covers PROVIDER_ENV_VARS', () => {
+  it('clears or redirects every provider data-dir override so a developer shell cannot leak real sessions into fixtures', () => {
+    const source = readFileSync(SETUP_PATH, 'utf8')
+    const isolated = new Set([
+      ...extractConstStringArray(source, 'CLEARED'),
+      ...extractConstStringArray(source, 'REDIRECTED'),
+    ])
+
+    const missing: string[] = []
+    for (const [provider, vars] of Object.entries(PROVIDER_ENV_VARS)) {
+      for (const varName of vars) {
+        if (!isolated.has(varName)) missing.push(`${provider}:${varName}`)
+      }
+    }
+
+    expect(missing).toEqual([])
+  })
+})
diff --git a/tests/setup/env-isolation.ts b/tests/setup/env-isolation.ts
index 6a3326ec..4c557a68 100644
--- a/tests/setup/env-isolation.ts
+++ b/tests/setup/env-isolation.ts
@@ -1,12 +1,13 @@
 // Vitest setup file: isolates every test from the developer's shell environment.
 //
 // codeburn discovers sessions through a long list of provider-specific env
-// vars (CLAUDE_CONFIG_DIR, CODEX_HOME, CRUSH_GLOBAL_DATA, …) and via HOME /
-// XDG_* / APPDATA / LOCALAPPDATA. Without this file, any value set in the
-// developer's shell (e.g. CLAUDE_CONFIG_DIRS=/Users/me/.claude:…) bleeds into
+// vars (CLAUDE_CONFIG_DIR, CODEX_HOME, HERMES_HOME, CRUSH_GLOBAL_DATA, …) and
+// via HOME / XDG_* / APPDATA / LOCALAPPDATA. Without this file, any value set
+// in the developer's shell (e.g. HERMES_HOME=/Users/me/.hermes) bleeds into
 // fixture-based tests: the parser reads the developer's REAL sessions instead
 // of the temp-dir fixture, producing nonsense totals and false failures that
-// pass on a clean CI runner.
+// pass on a clean CI runner. tests/env-isolation-declarations.test.ts fails
+// closed if PROVIDER_ENV_VARS grows a data-dir override that is not listed.
 //
 // What this file does:
 //   1. Mints an empty sandbox temp dir once per worker.
@@ -56,26 +57,36 @@ const CLEARED = [
   'CODEWHALE_HOME',
   'CRUSH_GLOBAL_DATA',
   'CODEBUFF_DATA_DIR',
+  'DSH_HOME',
   'FACTORY_DIR',
   'GOOSE_PATH_ROOT',
   'GROK_HOME',
+  'HERMES_HOME',
   'KIRO_HOME',
+  'KIMI_CODE_HOME',
   'KIMI_SHARE_DIR',
+  'LINGTAI_HOME',
+  'LINGTAI_TUI_GLOBAL_DIR',
+  'LINGTAI_TUI_HOME',
   'MUX_ROOT',
   'OPENCODE_DATA_DIR',
   'OPENCODE_DB_PREFIX',
+  'QUICKWORK_HOME',
   'QWEN_DATA_DIR',
   'VIBE_HOME',
   'WARP_DB_PATH',
   'ZS_DATA_DIR',
   // codeburn override dirs / paths
   'CODEBURN_CACHE_DIR',
+  'CODEBURN_COPILOT_GLOBAL_STORAGE_DIR',
   'CODEBURN_COPILOT_JETBRAINS_DIR',
   'CODEBURN_COPILOT_OTEL_DB',
   'CODEBURN_COPILOT_SESSION_STATE_DIR',
   'CODEBURN_COPILOT_WS_STORAGE_DIR',
   'CODEBURN_DESKTOP_SESSIONS_DIR',
   'CODEBURN_MUX_DIR',
+  'CODEBURN_OPEN_DESIGN_DIR',
+  'CODEBURN_OPENCLAUDE_DIR',
   'CODEBURN_ANTIGRAVITY_SETTINGS_PATH',
   // codeburn behavior toggles (set by the dev to tweak local runs)
   'CODEBURN_COPILOT_DISABLE_OTEL',