diff --git a/coderd/database/constants.go b/coderd/database/constants.go
index 931e0d7e09..34ad1005ee 100644
--- a/coderd/database/constants.go
+++ b/coderd/database/constants.go
@@ -1,5 +1,12 @@
 package database
 
-import "github.com/google/uuid"
+import (
+	"github.com/google/uuid"
 
-var PrebuildsSystemUserID = uuid.MustParse("c42fdf75-3097-471c-8c33-fb52454d81c0")
+	"github.com/coder/coder/v2/codersdk"
+)
+
+// PrebuildsSystemUserID mirrors codersdk.PrebuildsSystemUserID, parsed
+// for use as a uuid.UUID. Both must agree; tests pin the value to the
+// codersdk constant so the two cannot drift.
+var PrebuildsSystemUserID = uuid.MustParse(codersdk.PrebuildsSystemUserID)
diff --git a/codersdk/prebuilds.go b/codersdk/prebuilds.go
index 1f428d2f75..979c61bfb7 100644
--- a/codersdk/prebuilds.go
+++ b/codersdk/prebuilds.go
@@ -6,6 +6,13 @@ import (
 	"net/http"
 )
 
+// PrebuildsSystemUserID is the UUID of the Coder prebuilds system
+// user. Prebuilt workspaces are owned by this user until they are
+// claimed; build #1 of a claimed workspace remains attributed to
+// this user as the initiator forever, which is how callers can
+// recognize a prebuild claim after the fact.
+const PrebuildsSystemUserID = "c42fdf75-3097-471c-8c33-fb52454d81c0"
+
 type PrebuildsSettings struct {
 	ReconciliationPaused bool `json:"reconciliation_paused"`
 }
diff --git a/site/src/api/typesGenerated.ts b/site/src/api/typesGenerated.ts
index 6591ad23bf..7cf20be705 100644
--- a/site/src/api/typesGenerated.ts
+++ b/site/src/api/typesGenerated.ts
@@ -5922,6 +5922,16 @@ export interface PrebuildsSettings {
 	readonly reconciliation_paused: boolean;
 }
 
+// From codersdk/prebuilds.go
+/**
+ * PrebuildsSystemUserID is the UUID of the Coder prebuilds system
+ * user. Prebuilt workspaces are owned by this user until they are
+ * claimed; build #1 of a claimed workspace remains attributed to
+ * this user as the initiator forever, which is how callers can
+ * recognize a prebuild claim after the fact.
+ */
+export const PrebuildsSystemUserID = "c42fdf75-3097-471c-8c33-fb52454d81c0";
+
 // From codersdk/presets.go
 export interface Preset {
 	readonly ID: string;
diff --git a/site/src/pages/AgentsPage/AgentsPage.tsx b/site/src/pages/AgentsPage/AgentsPage.tsx
index 0799a089c1..aa3ce27ab7 100644
--- a/site/src/pages/AgentsPage/AgentsPage.tsx
+++ b/site/src/pages/AgentsPage/AgentsPage.tsx
@@ -340,6 +340,19 @@ const AgentsPage: FC = () => {
 		try {
 			const action = await resolveArchiveAndDeleteAction(
 				() => queryClient.fetchQuery(workspaceById(workspaceId)),
+				// We only need build_number 1 and 2 to recognise a
+				// prebuild claim. The default page is newest-first; the
+				// resolver degrades safely ("confirm") if those builds
+				// aren't in the returned slice.
+				() =>
+					queryClient.fetchQuery({
+						queryKey: [
+							"workspaceBuilds",
+							workspaceId,
+							"archive-and-delete-resolver",
+						],
+						queryFn: () => API.getWorkspaceBuilds(workspaceId),
+					}),
 				() =>
 					readInfiniteChatsCache(queryClient)?.find((c) => c.id === chatId)
 						?.created_at,
diff --git a/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.test.ts b/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.test.ts
index e45ac3bb95..f8820a3294 100644
--- a/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.test.ts
+++ b/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.test.ts
@@ -1,46 +1,204 @@
 import { describe, expect, it, vi } from "vitest";
+import { PrebuildsSystemUserID } from "#/api/typesGenerated";
 import {
 	archiveChatAndDeleteWorkspace,
 	isWorkspaceAutoCreated,
 	isWorkspaceNotFound,
 	resolveArchiveAndDeleteAction,
 	shouldNavigateAfterArchive,
+	workspaceAcquiredAt,
 } from "./agentWorkspaceUtils";
 
+const REAL_USER = "11111111-2222-3333-4444-555555555555";
+
+describe("workspaceAcquiredAt", () => {
+	it("returns workspace.created_at when no builds exist", () => {
+		const ws = { created_at: "2026-01-01T00:00:00Z" };
+		expect(workspaceAcquiredAt(ws, [])).toBe("2026-01-01T00:00:00Z");
+	});
+
+	it("returns workspace.created_at when build #1 was initiated by a real user", () => {
+		const ws = { created_at: "2026-01-01T00:00:00Z" };
+		const builds = [
+			{
+				build_number: 1,
+				initiator_id: REAL_USER,
+				created_at: "2026-01-01T00:00:01Z",
+			},
+		];
+		expect(workspaceAcquiredAt(ws, builds)).toBe("2026-01-01T00:00:00Z");
+	});
+
+	it("returns build #2 created_at when build #1 was initiated by the prebuilds user", () => {
+		// Workspace.created_at predates the chat (the prebuild was
+		// provisioned long before the chat existed), but build #2 is
+		// the claim and that's the moment the chat acquired the
+		// workspace.
+		const ws = { created_at: "2026-01-01T08:00:00Z" };
+		const builds = [
+			{
+				build_number: 2,
+				initiator_id: REAL_USER,
+				created_at: "2026-01-01T12:00:05Z",
+			},
+			{
+				build_number: 1,
+				initiator_id: PrebuildsSystemUserID,
+				created_at: "2026-01-01T08:00:01Z",
+			},
+		];
+		expect(workspaceAcquiredAt(ws, builds)).toBe("2026-01-01T12:00:05Z");
+	});
+
+	it("returns null when prebuild has no claim build yet", () => {
+		const ws = { created_at: "2026-01-01T08:00:00Z" };
+		const builds = [
+			{
+				build_number: 1,
+				initiator_id: PrebuildsSystemUserID,
+				created_at: "2026-01-01T08:00:01Z",
+			},
+		];
+		expect(workspaceAcquiredAt(ws, builds)).toBeNull();
+	});
+
+	it("ignores extra builds beyond #1 and #2", () => {
+		const ws = { created_at: "2026-01-01T08:00:00Z" };
+		const builds = [
+			{
+				build_number: 5,
+				initiator_id: REAL_USER,
+				created_at: "2026-02-01T00:00:00Z",
+			},
+			{
+				build_number: 4,
+				initiator_id: REAL_USER,
+				created_at: "2026-01-15T00:00:00Z",
+			},
+			{
+				build_number: 3,
+				initiator_id: REAL_USER,
+				created_at: "2026-01-10T00:00:00Z",
+			},
+			{
+				build_number: 2,
+				initiator_id: REAL_USER,
+				created_at: "2026-01-01T12:00:05Z",
+			},
+			{
+				build_number: 1,
+				initiator_id: PrebuildsSystemUserID,
+				created_at: "2026-01-01T08:00:01Z",
+			},
+		];
+		expect(workspaceAcquiredAt(ws, builds)).toBe("2026-01-01T12:00:05Z");
+	});
+});
+
 describe("isWorkspaceAutoCreated", () => {
 	it.each([
 		{
-			name: "workspace created after chat",
-			workspace: "2026-01-01T00:00:05Z",
+			name: "from-scratch workspace created after chat",
+			workspace: { created_at: "2026-01-01T00:00:05Z" },
+			builds: [
+				{
+					build_number: 1,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T00:00:05Z",
+				},
+			],
 			chat: "2026-01-01T00:00:00Z",
 			expected: true,
 		},
 		{
-			name: "workspace created at same time as chat",
-			workspace: "2026-01-01T12:00:00Z",
+			name: "from-scratch workspace created at same time as chat",
+			workspace: { created_at: "2026-01-01T12:00:00Z" },
+			builds: [
+				{
+					build_number: 1,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T12:00:00Z",
+				},
+			],
 			chat: "2026-01-01T12:00:00Z",
 			expected: true,
 		},
 		{
-			name: "workspace created before chat",
-			workspace: "2026-01-01T11:59:59Z",
+			name: "from-scratch workspace created before chat",
+			workspace: { created_at: "2026-01-01T11:59:59Z" },
+			builds: [
+				{
+					build_number: 1,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T11:59:59Z",
+				},
+			],
+			chat: "2026-01-01T12:00:00Z",
+			expected: false,
+		},
+		// Prebuild claim cases: workspace.created_at predates the
+		// chat, but build #2 (the claim) happened after the chat.
+		{
+			name: "prebuild claimed after chat",
+			workspace: { created_at: "2026-01-01T08:00:00Z" },
+			builds: [
+				{
+					build_number: 2,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T12:00:05Z",
+				},
+				{
+					build_number: 1,
+					initiator_id: PrebuildsSystemUserID,
+					created_at: "2026-01-01T08:00:01Z",
+				},
+			],
+			chat: "2026-01-01T12:00:00Z",
+			expected: true,
+		},
+		{
+			name: "prebuild claimed before chat",
+			workspace: { created_at: "2026-01-01T08:00:00Z" },
+			builds: [
+				{
+					build_number: 2,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T11:00:00Z",
+				},
+				{
+					build_number: 1,
+					initiator_id: PrebuildsSystemUserID,
+					created_at: "2026-01-01T08:00:01Z",
+				},
+			],
 			chat: "2026-01-01T12:00:00Z",
 			expected: false,
 		},
 		{
-			name: "sub-second precision difference",
-			workspace: "2026-01-01T00:00:00.001Z",
-			chat: "2026-01-01T00:00:00.000Z",
-			expected: true,
-		},
-		{
-			name: "workspace predates chat by days",
-			workspace: "2026-03-10T10:00:00Z",
-			chat: "2026-03-15T10:00:00Z",
+			name: "unclaimed prebuild treated as not auto-created",
+			workspace: { created_at: "2026-01-01T08:00:00Z" },
+			builds: [
+				{
+					build_number: 1,
+					initiator_id: PrebuildsSystemUserID,
+					created_at: "2026-01-01T08:00:01Z",
+				},
+			],
+			chat: "2026-01-01T12:00:00Z",
 			expected: false,
 		},
-	])("$name → $expected", ({ workspace, chat, expected }) => {
-		expect(isWorkspaceAutoCreated(workspace, chat)).toBe(expected);
+		{
+			// Defensive: build history empty. Fall back to
+			// workspace.created_at so we still allow the proceed
+			// path in the common case rather than blocking on data.
+			name: "no builds, falls back to workspace.created_at",
+			workspace: { created_at: "2026-01-01T12:00:05Z" },
+			builds: [],
+			chat: "2026-01-01T12:00:00Z",
+			expected: true,
+		},
+	])("$name → $expected", ({ workspace, builds, chat, expected }) => {
+		expect(isWorkspaceAutoCreated(workspace, builds, chat)).toBe(expected);
 	});
 });
 
@@ -221,31 +379,103 @@ describe("archiveChatAndDeleteWorkspace", () => {
 describe("resolveArchiveAndDeleteAction", () => {
 	it.each([
 		{
-			name: "auto-created workspace → proceed",
-			workspaceCreatedAt: "2026-01-01T00:00:05Z",
+			name: "from-scratch workspace created after chat → proceed",
+			workspace: { created_at: "2026-01-01T00:00:05Z" },
+			builds: [
+				{
+					build_number: 1,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T00:00:05Z",
+				},
+			],
 			chatCreatedAt: "2026-01-01T00:00:00Z",
 			expected: "proceed",
 		},
 		{
 			name: "workspace predates chat → confirm",
-			workspaceCreatedAt: "2025-12-01T00:00:00Z",
+			workspace: { created_at: "2025-12-01T00:00:00Z" },
+			builds: [
+				{
+					build_number: 1,
+					initiator_id: REAL_USER,
+					created_at: "2025-12-01T00:00:00Z",
+				},
+			],
 			chatCreatedAt: "2026-01-01T00:00:00Z",
 			expected: "confirm",
 		},
 		{
 			name: "chat not found in cache → confirm",
-			workspaceCreatedAt: "2026-01-01T00:00:05Z",
+			workspace: { created_at: "2026-01-01T00:00:05Z" },
+			builds: [
+				{
+					build_number: 1,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T00:00:05Z",
+				},
+			],
 			chatCreatedAt: undefined,
 			expected: "confirm",
 		},
-	])("$name", async ({ workspaceCreatedAt, chatCreatedAt, expected }) => {
+		{
+			// The bug this PR fixes: workspace.created_at predates
+			// the chat (the prebuild was provisioned earlier) but
+			// build #2 is the claim and happened after the chat.
+			name: "prebuild claimed after chat → proceed",
+			workspace: { created_at: "2025-12-15T00:00:00Z" },
+			builds: [
+				{
+					build_number: 2,
+					initiator_id: REAL_USER,
+					created_at: "2026-01-01T00:00:05Z",
+				},
+				{
+					build_number: 1,
+					initiator_id: PrebuildsSystemUserID,
+					created_at: "2025-12-15T00:00:00Z",
+				},
+			],
+			chatCreatedAt: "2026-01-01T00:00:00Z",
+			expected: "proceed",
+		},
+		{
+			name: "prebuild claimed before chat → confirm",
+			workspace: { created_at: "2025-12-15T00:00:00Z" },
+			builds: [
+				{
+					build_number: 2,
+					initiator_id: REAL_USER,
+					created_at: "2025-12-31T00:00:00Z",
+				},
+				{
+					build_number: 1,
+					initiator_id: PrebuildsSystemUserID,
+					created_at: "2025-12-15T00:00:00Z",
+				},
+			],
+			chatCreatedAt: "2026-01-01T00:00:00Z",
+			expected: "confirm",
+		},
+	])("$name", async ({ workspace, builds, chatCreatedAt, expected }) => {
 		const result = await resolveArchiveAndDeleteAction(
-			async () => ({ created_at: workspaceCreatedAt }),
+			async () => workspace,
+			async () => builds,
 			() => chatCreatedAt,
 		);
 		expect(result).toBe(expected);
 	});
 
+	it("does not fetch builds when the chat is not in the cache", async () => {
+		const fetchBuilds = vi.fn(async () => []);
+		const result = await resolveArchiveAndDeleteAction(
+			async () => ({ created_at: "2026-01-01T00:00:00Z" }),
+			fetchBuilds,
+			() => undefined,
+		);
+		expect(result).toBe("confirm");
+		expect(fetchBuilds).not.toHaveBeenCalled();
+	});
+
 	it("propagates non-404-or-410 workspace fetch errors", async () => {
 		const error = {
 			isAxiosError: true,
@@ -260,6 +490,7 @@ describe("resolveArchiveAndDeleteAction", () => {
 				async () => {
 					throw error;
 				},
+				async () => [],
 				() => "2026-01-01T00:00:00Z",
 			),
 		).rejects.toBe(error);
@@ -279,6 +510,7 @@ describe("resolveArchiveAndDeleteAction", () => {
 				async () => {
 					throw error;
 				},
+				async () => [],
 				() => "2026-01-01T00:00:00Z",
 			),
 		).resolves.toBe("archive-only");
@@ -298,10 +530,51 @@ describe("resolveArchiveAndDeleteAction", () => {
 				async () => {
 					throw error;
 				},
+				async () => [],
 				() => "2026-01-01T00:00:00Z",
 			),
 		).resolves.toBe("archive-only");
 	});
+
+	it("returns archive-only when the builds fetch returns 404", async () => {
+		const error = {
+			isAxiosError: true,
+			response: {
+				status: 404,
+				data: { message: "Workspace not found" },
+			},
+		};
+
+		await expect(
+			resolveArchiveAndDeleteAction(
+				async () => ({ created_at: "2026-01-01T00:00:00Z" }),
+				async () => {
+					throw error;
+				},
+				() => "2026-01-01T00:00:00Z",
+			),
+		).resolves.toBe("archive-only");
+	});
+
+	it("propagates non-404-or-410 builds fetch errors", async () => {
+		const error = {
+			isAxiosError: true,
+			response: {
+				status: 500,
+				data: { message: "Internal server error" },
+			},
+		};
+
+		await expect(
+			resolveArchiveAndDeleteAction(
+				async () => ({ created_at: "2026-01-01T00:00:00Z" }),
+				async () => {
+					throw error;
+				},
+				() => "2026-01-01T00:00:00Z",
+			),
+		).rejects.toBe(error);
+	});
 });
 
 describe("shouldNavigateAfterArchive", () => {
diff --git a/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.ts b/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.ts
index c49472885a..c2566e31e5 100644
--- a/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.ts
+++ b/site/src/pages/AgentsPage/utils/agentWorkspaceUtils.ts
@@ -1,17 +1,70 @@
 import { isAxiosError } from "axios";
+import {
+	PrebuildsSystemUserID,
+	type WorkspaceBuild,
+} from "#/api/typesGenerated";
 
 /**
- * Determines whether a workspace was auto-created by a chat.
- * Workspaces created at or after the chat's creation time are
- * considered auto-created (the chat provisioned them). Pre-existing
- * workspaces that were manually associated need a confirmation
- * dialog before deletion.
+ * Returns the moment a workspace's identity transferred to its
+ * current owner.
+ *
+ * For workspaces created from scratch, this is `workspace.created_at`:
+ * build #1 already belongs to the current owner.
+ *
+ * For workspaces claimed from a prebuild, this is the start time of
+ * build #2 (the claim build). `workspace.created_at` for those
+ * workspaces reflects when the prebuild was provisioned, often well
+ * before the chat that claimed it existed, which is why the original
+ * `created_at` heuristic misfired the deletion confirmation dialog.
+ *
+ * Returns `null` when the result cannot be determined, for example
+ * an unclaimed prebuild (build #1 by prebuilds system user, no build
+ * #2). Callers should treat `null` as "force the confirmation
+ * dialog"; the deletion path is destructive and should err on the
+ * side of asking.
+ */
+export function workspaceAcquiredAt(
+	workspace: { created_at: string },
+	builds: readonly Pick<
+		WorkspaceBuild,
+		"build_number" | "initiator_id" | "created_at"
+	>[],
+): string | null {
+	const build1 = builds.find((b) => b.build_number === 1);
+	// No history at all (shouldn't happen for an existing workspace);
+	// fall back to created_at rather than blocking on missing data.
+	if (!build1) {
+		return workspace.created_at;
+	}
+	if (build1.initiator_id !== PrebuildsSystemUserID) {
+		return workspace.created_at;
+	}
+	const build2 = builds.find((b) => b.build_number === 2);
+	return build2 ? build2.created_at : null;
+}
+
+/**
+ * Determines whether a workspace was auto-created by a chat. A
+ * workspace is "auto-created" if the chat acquired it (via creation
+ * from scratch or by claiming a prebuild) at or after the chat's own
+ * creation time.
+ *
+ * Pre-existing workspaces that were manually associated with the
+ * chat need a confirmation dialog before deletion.
  */
 export function isWorkspaceAutoCreated(
-	workspaceCreatedAt: string,
+	workspace: { created_at: string },
+	builds: readonly Pick<
+		WorkspaceBuild,
+		"build_number" | "initiator_id" | "created_at"
+	>[],
 	chatCreatedAt: string,
 ): boolean {
-	return new Date(workspaceCreatedAt) >= new Date(chatCreatedAt);
+	const acquiredAt = workspaceAcquiredAt(workspace, builds);
+	if (acquiredAt === null) {
+		return false;
+	}
+	return new Date(acquiredAt) >= new Date(chatCreatedAt);
 }
 
 /**
@@ -78,14 +131,18 @@ export function shouldNavigateAfterArchive(
 /**
  * Resolves whether an archive-and-delete action should proceed
  * immediately or require user confirmation. Fetches the workspace
- * to compare its creation time against the chat's. Auto-created
- * workspaces (provisioned by the chat) skip the confirmation
- * dialog; pre-existing workspaces require the user to type the
- * workspace name.
+ * and its build history to determine when the workspace was
+ * acquired (claim time for prebuilts, creation time otherwise) and
+ * compares against the chat's creation time. Auto-created
+ * workspaces (provisioned or claimed by the chat) skip the
+ * confirmation dialog; pre-existing workspaces require the user to
+ * type the workspace name.
  *
  * @param fetchWorkspace - Retrieves the workspace (e.g. via
- *   `queryClient.fetchQuery`). The result must include
- *   `created_at`.
+ *   `queryClient.fetchQuery`). The result must include `created_at`.
+ * @param fetchBuilds - Retrieves the workspace's build history. The
+ *   first call only needs build_number 1 and 2, but callers will
+ *   typically pass the full list.
  * @param getChatCreatedAt - Returns the chat's `created_at`
  *   timestamp, or `undefined` if the chat is not in the cache.
  * @returns `"proceed"` to skip the dialog, `"archive-only"` to archive
@@ -94,6 +151,12 @@ export function shouldNavigateAfterArchive(
  */
 export async function resolveArchiveAndDeleteAction(
 	fetchWorkspace: () => Promise<{ created_at: string }>,
+	fetchBuilds: () => Promise<
+		readonly Pick<
+			WorkspaceBuild,
+			"build_number" | "initiator_id" | "created_at"
+		>[]
+	>,
 	getChatCreatedAt: () => string | undefined,
 ): Promise<"proceed" | "confirm" | "archive-only"> {
 	let workspace: { created_at: string };
@@ -106,10 +169,22 @@ export async function resolveArchiveAndDeleteAction(
 		throw error;
 	}
 	const chatCreatedAt = getChatCreatedAt();
-	if (
-		chatCreatedAt &&
-		isWorkspaceAutoCreated(workspace.created_at, chatCreatedAt)
-	) {
+	if (!chatCreatedAt) {
+		return "confirm";
+	}
+	let builds: readonly Pick<
+		WorkspaceBuild,
+		"build_number" | "initiator_id" | "created_at"
+	>[];
+	try {
+		builds = await fetchBuilds();
+	} catch (error) {
+		if (isWorkspaceNotFound(error)) {
+			return "archive-only";
+		}
+		throw error;
+	}
+	if (isWorkspaceAutoCreated(workspace, builds, chatCreatedAt)) {
 		return "proceed";
 	}
 	return "confirm";