diff --git a/src/tools/agent-teams/inbox-store.test.ts b/src/tools/agent-teams/inbox-store.test.ts
new file mode 100644
index 00000000..9a419500
--- /dev/null
+++ b/src/tools/agent-teams/inbox-store.test.ts
@@ -0,0 +1,59 @@
+/// <reference types="bun-types" />
+import { afterEach, beforeEach, describe, expect, test } from "bun:test"
+import { mkdtempSync, readFileSync, rmSync, writeFileSync } from "node:fs"
+import { tmpdir } from "node:os"
+import { join } from "node:path"
+import { appendInboxMessage, ensureInbox, readInbox } from "./inbox-store"
+import { getTeamInboxPath } from "./paths"
+
+describe("agent-teams inbox store", () => {
+  let originalCwd: string
+  let tempProjectDir: string
+
+  beforeEach(() => {
+    originalCwd = process.cwd()
+    tempProjectDir = mkdtempSync(join(tmpdir(), "agent-teams-inbox-store-"))
+    process.chdir(tempProjectDir)
+  })
+
+  afterEach(() => {
+    process.chdir(originalCwd)
+    rmSync(tempProjectDir, { recursive: true, force: true })
+  })
+
+  test("readInbox fails on malformed inbox JSON without overwriting file", () => {
+    //#given
+    ensureInbox("core", "team-lead")
+    const inboxPath = getTeamInboxPath("core", "team-lead")
+    writeFileSync(inboxPath, "{", "utf-8")
+
+    //#when
+    const readMalformedInbox = () => readInbox("core", "team-lead", false, false)
+
+    //#then
+    expect(readMalformedInbox).toThrow("team_inbox_parse_failed")
+    expect(readFileSync(inboxPath, "utf-8")).toBe("{")
+  })
+
+  test("appendInboxMessage fails on schema-invalid inbox JSON without overwriting file", () => {
+    //#given
+    ensureInbox("core", "team-lead")
+    const inboxPath = getTeamInboxPath("core", "team-lead")
+    writeFileSync(inboxPath, JSON.stringify({ invalid: true }), "utf-8")
+
+    //#when
+    const appendIntoInvalidInbox = () => {
+      appendInboxMessage("core", "team-lead", {
+        from: "team-lead",
+        text: "hello",
+        timestamp: new Date().toISOString(),
+        read: false,
+        summary: "note",
+      })
+    }
+
+    //#then
+    expect(appendIntoInvalidInbox).toThrow("team_inbox_schema_invalid")
+    expect(readFileSync(inboxPath, "utf-8")).toBe(JSON.stringify({ invalid: true }))
+  })
+})
diff --git a/src/tools/agent-teams/inbox-store.ts b/src/tools/agent-teams/inbox-store.ts
index 4b9fbfdb..3a6b1019 100644
--- a/src/tools/agent-teams/inbox-store.ts
+++ b/src/tools/agent-teams/inbox-store.ts
@@ -42,13 +42,20 @@ function withInboxLock<T>(teamName: string, operation: () => T): T {
 }
 
 function parseInboxFile(content: string): TeamInboxMessage[] {
+  let parsed: unknown
+
   try {
-    const parsed = JSON.parse(content)
-    const result = TeamInboxListSchema.safeParse(parsed)
-    return result.success ? result.data : []
+    parsed = JSON.parse(content)
   } catch {
-    return []
+    throw new Error("team_inbox_parse_failed")
   }
+
+  const result = TeamInboxListSchema.safeParse(parsed)
+  if (!result.success) {
+    throw new Error("team_inbox_schema_invalid")
+  }
+
+  return result.data
 }
 
 function readInboxMessages(teamName: string, agentName: string): TeamInboxMessage[] {
diff --git a/src/tools/agent-teams/team-config-store.test.ts b/src/tools/agent-teams/team-config-store.test.ts
index 254056ab..7b6a50e0 100644
--- a/src/tools/agent-teams/team-config-store.test.ts
+++ b/src/tools/agent-teams/team-config-store.test.ts
@@ -1,10 +1,10 @@
 /// <reference types="bun-types" />
 import { afterEach, beforeEach, describe, expect, test } from "bun:test"
-import { mkdtempSync, readFileSync, rmSync } from "node:fs"
+import { chmodSync, existsSync, mkdtempSync, rmSync } from "node:fs"
 import { tmpdir } from "node:os"
 import { join } from "node:path"
 import { acquireLock } from "../../features/claude-tasks/storage"
-import { getTeamDir, getTeamTaskDir } from "./paths"
+import { getTeamDir, getTeamTaskDir, getTeamsRootDir } from "./paths"
 import { createTeamConfig, deleteTeamData, teamExists } from "./team-config-store"
 
 describe("agent-teams team config store", () => {
@@ -69,21 +69,26 @@ describe("agent-teams team config store", () => {
     expect(teamExists("core")).toBe(false)
   })
 
-  test("deleteTeamData removes task files before team files", () => {
+  test("deleteTeamData removes task files before deleting team directory", () => {
     //#given
-    const sourceUrl = new URL("./team-config-store.ts", import.meta.url)
-    const source = readFileSync(sourceUrl, "utf-8")
-    const deleteFnStart = source.indexOf("export function deleteTeamData")
-    const deleteFnSlice = deleteFnStart >= 0 ? source.slice(deleteFnStart, deleteFnStart + 700) : ""
+    const taskDir = getTeamTaskDir("core")
+    const teamDir = getTeamDir("core")
+    const teamsRootDir = getTeamsRootDir()
+    expect(existsSync(taskDir)).toBe(true)
+    expect(existsSync(teamDir)).toBe(true)
 
     //#when
-    const taskDeleteIndex = deleteFnSlice.indexOf("rmSync(taskDir")
-    const teamDeleteIndex = deleteFnSlice.indexOf("rmSync(teamDir")
+    chmodSync(teamsRootDir, 0o555)
+    try {
+      const deleteWithBlockedTeamParent = () => deleteTeamData("core")
+      expect(deleteWithBlockedTeamParent).toThrow()
+    } finally {
+      chmodSync(teamsRootDir, 0o755)
+    }
 
     //#then
-    expect(deleteFnStart).toBeGreaterThanOrEqual(0)
-    expect(taskDeleteIndex).toBeGreaterThanOrEqual(0)
-    expect(teamDeleteIndex).toBeGreaterThanOrEqual(0)
-    expect(taskDeleteIndex).toBeLessThan(teamDeleteIndex)
+    expect(existsSync(taskDir)).toBe(false)
+    expect(existsSync(teamDir)).toBe(true)
   })
+
 })
diff --git a/src/tools/agent-teams/teammate-parent-context.test.ts b/src/tools/agent-teams/teammate-parent-context.test.ts
index 8ad11e28..6654d491 100644
--- a/src/tools/agent-teams/teammate-parent-context.test.ts
+++ b/src/tools/agent-teams/teammate-parent-context.test.ts
@@ -1,14 +1,24 @@
 /// <reference types="bun-types" />
 import { describe, expect, test } from "bun:test"
-import { readFileSync } from "node:fs"
+import { buildTeamParentToolContext } from "./teammate-parent-context"
 
 describe("agent-teams teammate parent context", () => {
   test("forwards incoming abort signal to parent context resolver", () => {
     //#given
-    const sourceUrl = new URL("./teammate-parent-context.ts", import.meta.url)
-    const source = readFileSync(sourceUrl, "utf-8")
+    const abortSignal = new AbortController().signal
+
+    //#when
+    const parentToolContext = buildTeamParentToolContext({
+      sessionID: "ses-main",
+      messageID: "msg-main",
+      agent: "sisyphus",
+      abort: abortSignal,
+    })
 
     //#then
-    expect(source.includes("abort: context.abort ?? new AbortController().signal")).toBe(true)
+    expect(parentToolContext.abort).toBe(abortSignal)
+    expect(parentToolContext.sessionID).toBe("ses-main")
+    expect(parentToolContext.messageID).toBe("msg-main")
+    expect(parentToolContext.agent).toBe("sisyphus")
   })
 })
diff --git a/src/tools/agent-teams/teammate-parent-context.ts b/src/tools/agent-teams/teammate-parent-context.ts
index 59e5f63e..129e9ba1 100644
--- a/src/tools/agent-teams/teammate-parent-context.ts
+++ b/src/tools/agent-teams/teammate-parent-context.ts
@@ -3,11 +3,15 @@ import { resolveParentContext } from "../delegate-task/executor"
 import type { ToolContextWithMetadata } from "../delegate-task/types"
 import type { TeamToolContext } from "./types"
 
-export function resolveTeamParentContext(context: TeamToolContext): ParentContext {
-  return resolveParentContext({
+export function buildTeamParentToolContext(context: TeamToolContext): ToolContextWithMetadata {
+  return {
     sessionID: context.sessionID,
     messageID: context.messageID,
     agent: context.agent ?? "sisyphus",
     abort: context.abort ?? new AbortController().signal,
-  } as ToolContextWithMetadata)
+  }
+}
+
+export function resolveTeamParentContext(context: TeamToolContext): ParentContext {
+  return resolveParentContext(buildTeamParentToolContext(context))
 }