diff --git a/bun.lock b/bun.lock
index b46c485..f749bec 100644
--- a/bun.lock
+++ b/bun.lock
@@ -249,7 +249,7 @@
       },
       "devDependencies": {
         "@cyrus/typescript": "workspace:*",
-        "@types/bun": "catalog:",
+        "vitest": "catalog:",
       },
     },
     "shared/constants": {
@@ -259,6 +259,7 @@
         "@cyrus/typescript": "workspace:*",
         "@types/bun": "catalog:",
         "typescript": "catalog:",
+        "vitest": "catalog:",
       },
     },
     "shared/database": {
@@ -280,6 +281,7 @@
         "@tursodatabase/database": "^0.6.1",
         "@types/bun": "catalog:",
         "typescript": "catalog:",
+        "vitest": "catalog:",
       },
     },
     "shared/errors": {
@@ -360,6 +362,7 @@
       "devDependencies": {
         "@cyrus/typescript": "workspace:*",
         "@types/bun": "catalog:",
+        "vitest": "catalog:",
       },
     },
     "shared/styles": {
@@ -381,6 +384,7 @@
         "@cyrus/typescript": "workspace:*",
         "@types/bun": "catalog:",
         "typescript": "catalog:",
+        "vitest": "catalog:",
       },
     },
     "tests/e2e": {
diff --git a/shared/connections/package.json b/shared/connections/package.json
index e3ac4ed..97ddcba 100644
--- a/shared/connections/package.json
+++ b/shared/connections/package.json
@@ -8,7 +8,7 @@
     "./rtc/worker": "./src/rtc/worker/index.ts"
   },
   "scripts": {
-    "test:unit": "bun test"
+    "test:unit": "vitest run"
   },
   "dependencies": {
     "@cyrus/errors": "workspace:*",
@@ -24,6 +24,6 @@
   },
   "devDependencies": {
     "@cyrus/typescript": "workspace:*",
-    "@types/bun": "catalog:"
+    "vitest": "catalog:"
   }
 }
diff --git a/shared/connections/src/rtc/peer.test.ts b/shared/connections/src/rtc/peer.test.ts
index 8c7298f..46a5607 100644
--- a/shared/connections/src/rtc/peer.test.ts
+++ b/shared/connections/src/rtc/peer.test.ts
@@ -1,5 +1,5 @@
-import { describe, expect, test } from "bun:test";
 import type { ServerEvent } from "@cyrus/schemas/signaling";
+import { describe, expect, test } from "vitest";
 import { createSignalingEvents } from "./peer";
 
 async function* eventStream(events: ServerEvent[]) {
diff --git a/shared/connections/src/rtc/session.test.ts b/shared/connections/src/rtc/session.test.ts
index bcfd106..abb131e 100644
--- a/shared/connections/src/rtc/session.test.ts
+++ b/shared/connections/src/rtc/session.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import { normalizeHost } from "./session";
 
 describe("normalizeHost", () => {
diff --git a/shared/connections/src/rtc/webrtc-nightly.test.ts b/shared/connections/src/rtc/webrtc-nightly.test.ts
index 1619d30..c1d8b4b 100644
--- a/shared/connections/src/rtc/webrtc-nightly.test.ts
+++ b/shared/connections/src/rtc/webrtc-nightly.test.ts
@@ -1,5 +1,5 @@
-import { describe, expect, test } from "bun:test";
 import { RTCPeerConnection as NodeRTCPeerConnection } from "node-datachannel/polyfill";
+import { describe, expect, test } from "vitest";
 
 const nightlyDescribe =
 	process.env.CYRUS_NIGHTLY_WEBRTC === "1" ? describe : describe.skip;
diff --git a/shared/connections/tsconfig.json b/shared/connections/tsconfig.json
index 542570d..314522d 100644
--- a/shared/connections/tsconfig.json
+++ b/shared/connections/tsconfig.json
@@ -6,6 +6,6 @@
     "types": [],
     "strictNullChecks": true
   },
-  "include": ["src/**/*.ts", "src/**/*.tsx"],
+  "include": ["src/**/*.ts", "src/**/*.tsx", "vitest.config.ts"],
   "exclude": ["node_modules"]
 }
diff --git a/shared/connections/vitest.config.ts b/shared/connections/vitest.config.ts
new file mode 100644
index 0000000..cfbd4c3
--- /dev/null
+++ b/shared/connections/vitest.config.ts
@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+	test: {
+		environment: "node",
+		include: ["src/**/*.test.ts"],
+	},
+});
diff --git a/shared/constants/package.json b/shared/constants/package.json
index 7a04118..70c714c 100644
--- a/shared/constants/package.json
+++ b/shared/constants/package.json
@@ -8,11 +8,12 @@
   },
   "scripts": {
     "check:types": "tsc --noEmit",
-    "test:unit": "bun test"
+    "test:unit": "vitest run"
   },
   "devDependencies": {
     "@cyrus/typescript": "workspace:*",
     "@types/bun": "catalog:",
-    "typescript": "catalog:"
+    "typescript": "catalog:",
+    "vitest": "catalog:"
   }
 }
diff --git a/shared/constants/src/operation-keys.test.ts b/shared/constants/src/operation-keys.test.ts
index 01e6067..5340587 100644
--- a/shared/constants/src/operation-keys.test.ts
+++ b/shared/constants/src/operation-keys.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import {
 	AUTH_OPERATION_KEYS,
 	RTC_OPERATION_KEYS,
diff --git a/shared/constants/tsconfig.json b/shared/constants/tsconfig.json
index 449b871..1d89f84 100644
--- a/shared/constants/tsconfig.json
+++ b/shared/constants/tsconfig.json
@@ -4,6 +4,6 @@
     "types": ["bun"],
     "strictNullChecks": true
   },
-  "include": ["src/**/*.ts"],
+  "include": ["src/**/*.ts", "vitest.config.ts"],
   "exclude": ["node_modules"]
 }
diff --git a/shared/constants/vitest.config.ts b/shared/constants/vitest.config.ts
new file mode 100644
index 0000000..cfbd4c3
--- /dev/null
+++ b/shared/constants/vitest.config.ts
@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+	test: {
+		environment: "node",
+		include: ["src/**/*.test.ts"],
+	},
+});
diff --git a/shared/database/__tests__/integration/repositories.test.ts b/shared/database/__tests__/integration/repositories.test.ts
index 0410d3d..d600dc6 100644
--- a/shared/database/__tests__/integration/repositories.test.ts
+++ b/shared/database/__tests__/integration/repositories.test.ts
@@ -1,4 +1,3 @@
-import { describe, expect, test } from "bun:test";
 import {
 	appendConversation,
 	getConversations,
@@ -16,6 +15,7 @@ import {
 	renameThread,
 	threadNameFromPrompt,
 } from "@cyrus/database/repositories/threads";
+import { describe, expect, test } from "vitest";
 import { withTempDatabase } from "../helpers/turso";
 
 describe("database repositories", () => {
diff --git a/shared/database/package.json b/shared/database/package.json
index b694a0b..3734600 100644
--- a/shared/database/package.json
+++ b/shared/database/package.json
@@ -10,7 +10,8 @@
     "check:types": "tsc --noEmit",
     "db:push": "dotenvx run -- drizzle-kit push",
     "db:studio": "dotenvx run -- drizzle-kit studio",
-    "test:integration": "bun test __tests__/integration"
+    "test:unit": "vitest run src",
+    "test:integration": "vitest run __tests__/integration"
   },
   "dependencies": {
     "@cyrus/errors": "workspace:*",
@@ -27,6 +28,7 @@
     "@cyrus/typescript": "workspace:*",
     "@tursodatabase/database": "^0.6.1",
     "@types/bun": "catalog:",
-    "typescript": "catalog:"
+    "typescript": "catalog:",
+    "vitest": "catalog:"
   }
 }
diff --git a/shared/database/src/utils/repo.test.ts b/shared/database/src/utils/repo.test.ts
index 49e85a6..0848eb1 100644
--- a/shared/database/src/utils/repo.test.ts
+++ b/shared/database/src/utils/repo.test.ts
@@ -1,4 +1,3 @@
-import { describe, expect, test } from "bun:test";
 import {
 	notFound,
 	persistFailed,
@@ -7,6 +6,7 @@ import {
 	RepositoryPersistFailedError,
 } from "@cyrus/errors/repository";
 import { DrizzleQueryError } from "drizzle-orm";
+import { describe, expect, test } from "vitest";
 import { z } from "zod";
 import {
 	fromDrizzleFailure,
diff --git a/shared/database/tsconfig.json b/shared/database/tsconfig.json
index 3d4b31e..ca2dc6a 100644
--- a/shared/database/tsconfig.json
+++ b/shared/database/tsconfig.json
@@ -6,6 +6,11 @@
     "types": ["bun"],
     "strictNullChecks": true
   },
-  "include": ["src/**/*.ts", "src/**/*.tsx", "__tests__/**/*.ts"],
+  "include": [
+    "src/**/*.ts",
+    "src/**/*.tsx",
+    "__tests__/**/*.ts",
+    "vitest.config.ts"
+  ],
   "exclude": ["node_modules"]
 }
diff --git a/shared/database/vitest.config.ts b/shared/database/vitest.config.ts
new file mode 100644
index 0000000..6e8ef85
--- /dev/null
+++ b/shared/database/vitest.config.ts
@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+	test: {
+		environment: "node",
+		include: ["src/**/*.test.ts", "__tests__/integration/**/*.test.ts"],
+	},
+});
diff --git a/shared/schemas/package.json b/shared/schemas/package.json
index 5651cad..5170690 100644
--- a/shared/schemas/package.json
+++ b/shared/schemas/package.json
@@ -10,13 +10,14 @@
     "./signaling": "./src/signaling.ts"
   },
   "scripts": {
-    "test:unit": "bun test"
+    "test:unit": "vitest run"
   },
   "dependencies": {
     "zod": "catalog:"
   },
   "devDependencies": {
     "@cyrus/typescript": "workspace:*",
-    "@types/bun": "catalog:"
+    "@types/bun": "catalog:",
+    "vitest": "catalog:"
   }
 }
diff --git a/shared/schemas/src/rtc/agents.test.ts b/shared/schemas/src/rtc/agents.test.ts
index fda9cd6..7b11978 100644
--- a/shared/schemas/src/rtc/agents.test.ts
+++ b/shared/schemas/src/rtc/agents.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import { ListAgentsOutputSchema } from "./agents";
 
 describe("ListAgentsOutputSchema", () => {
diff --git a/shared/schemas/src/rtc/chat.test.ts b/shared/schemas/src/rtc/chat.test.ts
index e0edc1c..9ffa3b4 100644
--- a/shared/schemas/src/rtc/chat.test.ts
+++ b/shared/schemas/src/rtc/chat.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import {
 	AgentEventSchema,
 	ChatChunkSchema,
diff --git a/shared/schemas/src/rtc/threads.test.ts b/shared/schemas/src/rtc/threads.test.ts
index 0aab2b7..f37e1bf 100644
--- a/shared/schemas/src/rtc/threads.test.ts
+++ b/shared/schemas/src/rtc/threads.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import {
 	ConversationEntrySchema,
 	RenameThreadInputSchema,
diff --git a/shared/schemas/src/signaling.test.ts b/shared/schemas/src/signaling.test.ts
index 9b2dee1..25ca942 100644
--- a/shared/schemas/src/signaling.test.ts
+++ b/shared/schemas/src/signaling.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import {
 	DeviceInfoSchema,
 	DeviceRoleSchema,
diff --git a/shared/schemas/tsconfig.json b/shared/schemas/tsconfig.json
index 4716ed9..a38e411 100644
--- a/shared/schemas/tsconfig.json
+++ b/shared/schemas/tsconfig.json
@@ -6,6 +6,6 @@
     "types": ["bun"],
     "strictNullChecks": true
   },
-  "include": ["src/**/*.ts", "src/**/*.tsx"],
+  "include": ["src/**/*.ts", "src/**/*.tsx", "vitest.config.ts"],
   "exclude": ["node_modules"]
 }
diff --git a/shared/schemas/vitest.config.ts b/shared/schemas/vitest.config.ts
new file mode 100644
index 0000000..cfbd4c3
--- /dev/null
+++ b/shared/schemas/vitest.config.ts
@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+	test: {
+		environment: "node",
+		include: ["src/**/*.test.ts"],
+	},
+});
diff --git a/shared/utils/package.json b/shared/utils/package.json
index 770d75d..a17e09d 100644
--- a/shared/utils/package.json
+++ b/shared/utils/package.json
@@ -7,7 +7,7 @@
     "./*": "./src/*.ts"
   },
   "scripts": {
-    "test:unit": "bun test"
+    "test:unit": "vitest run"
   },
   "dependencies": {
     "@cyrus/errors": "workspace:*",
@@ -20,6 +20,7 @@
   "devDependencies": {
     "@cyrus/typescript": "workspace:*",
     "@types/bun": "catalog:",
-    "typescript": "catalog:"
+    "typescript": "catalog:",
+    "vitest": "catalog:"
   }
 }
diff --git a/shared/utils/src/conversations/fold.test.ts b/shared/utils/src/conversations/fold.test.ts
index 1a092aa..14853d5 100644
--- a/shared/utils/src/conversations/fold.test.ts
+++ b/shared/utils/src/conversations/fold.test.ts
@@ -1,6 +1,6 @@
-import { describe, expect, test } from "bun:test";
 import type { AgentEvent } from "@cyrus/schemas/rtc/chat";
 import type { ConversationEntry } from "@cyrus/schemas/rtc/threads";
+import { describe, expect, test } from "vitest";
 import { fold } from "./fold";
 
 function entry(
diff --git a/shared/utils/src/conversations/thread-feed.test.ts b/shared/utils/src/conversations/thread-feed.test.ts
index 53d5b6b..614f85c 100644
--- a/shared/utils/src/conversations/thread-feed.test.ts
+++ b/shared/utils/src/conversations/thread-feed.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import { deriveFeed } from "./thread-feed";
 
 describe("deriveFeed", () => {
diff --git a/shared/utils/src/conversations/turn-waiters.test.ts b/shared/utils/src/conversations/turn-waiters.test.ts
index 718d7b2..cef35e6 100644
--- a/shared/utils/src/conversations/turn-waiters.test.ts
+++ b/shared/utils/src/conversations/turn-waiters.test.ts
@@ -1,5 +1,5 @@
-import { describe, expect, test } from "bun:test";
 import { isTurnInterruptedError, turnWaitFailed } from "@cyrus/errors/turn";
+import { describe, expect, test } from "vitest";
 import {
 	rejectTurnWaiter,
 	settleTurnWaiter,
diff --git a/shared/utils/src/identity.test.ts b/shared/utils/src/identity.test.ts
index 9749507..530a825 100644
--- a/shared/utils/src/identity.test.ts
+++ b/shared/utils/src/identity.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import { generateName, randomId } from "./identity";
 
 const UUID_PATTERN =
diff --git a/shared/utils/src/path.test.ts b/shared/utils/src/path.test.ts
index 0314412..3f695c6 100644
--- a/shared/utils/src/path.test.ts
+++ b/shared/utils/src/path.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import {
 	appendBrowsePathSegment,
 	canNavigateUp,
diff --git a/shared/utils/src/timer.test.ts b/shared/utils/src/timer.test.ts
index 3035fe2..35cb0c5 100644
--- a/shared/utils/src/timer.test.ts
+++ b/shared/utils/src/timer.test.ts
@@ -1,4 +1,4 @@
-import { describe, expect, test } from "bun:test";
+import { describe, expect, test } from "vitest";
 import { formatElapsedTimer, formatElapsedTimerNow } from "./timer";
 
 describe("timer helpers", () => {
diff --git a/shared/utils/tsconfig.json b/shared/utils/tsconfig.json
index 4716ed9..a38e411 100644
--- a/shared/utils/tsconfig.json
+++ b/shared/utils/tsconfig.json
@@ -6,6 +6,6 @@
     "types": ["bun"],
     "strictNullChecks": true
   },
-  "include": ["src/**/*.ts", "src/**/*.tsx"],
+  "include": ["src/**/*.ts", "src/**/*.tsx", "vitest.config.ts"],
   "exclude": ["node_modules"]
 }
diff --git a/shared/utils/vitest.config.ts b/shared/utils/vitest.config.ts
new file mode 100644
index 0000000..cfbd4c3
--- /dev/null
+++ b/shared/utils/vitest.config.ts
@@ -0,0 +1,8 @@
+import { defineConfig } from "vitest/config";
+
+export default defineConfig({
+	test: {
+		environment: "node",
+		include: ["src/**/*.test.ts"],
+	},
+});
diff --git a/vitest.config.ts b/vitest.config.ts
index f16d0d4..de9ab8e 100644
--- a/vitest.config.ts
+++ b/vitest.config.ts
@@ -5,8 +5,13 @@ export default defineConfig({
 		projects: [
 			"apps/web/vitest.config.ts",
 			"apps/server/vitest.config.ts",
+			"shared/connections/vitest.config.ts",
+			"shared/constants/vitest.config.ts",
+			"shared/database/vitest.config.ts",
 			"shared/hooks/vitest.config.ts",
 			"shared/providers/vitest.config.ts",
+			"shared/schemas/vitest.config.ts",
+			"shared/utils/vitest.config.ts",
 		],
 		coverage: {
 			provider: "istanbul",