diff --git a/server/src/__tests__/build-commit.test.ts b/server/src/__tests__/build-commit.test.ts
new file mode 100644
index 0000000000..f76dc8505c
--- /dev/null
+++ b/server/src/__tests__/build-commit.test.ts
@@ -0,0 +1,42 @@
+import { describe, expect, it, vi } from "vitest";
+import { parseBuildCommit, readBuildCommit } from "../build-commit.js";
+
+describe("parseBuildCommit", () => {
+  it("normalizes a full deployment commit", () => {
+    expect(parseBuildCommit("  ABCDEF0123456789ABCDEF0123456789ABCDEF01\n")).toBe(
+      "abcdef0123456789abcdef0123456789abcdef01",
+    );
+  });
+
+  it("rejects truncated and malformed commits", () => {
+    expect(parseBuildCommit("abcdef0")).toBeNull();
+    expect(parseBuildCommit("not-a-commit")).toBeNull();
+  });
+});
+
+describe("readBuildCommit", () => {
+  it("prefers an explicit environment commit", () => {
+    const readTextFile = vi.fn(() => "ffffffffffffffffffffffffffffffffffffffff");
+
+    expect(
+      readBuildCommit({
+        environmentCommit: "0123456789abcdef0123456789abcdef01234567",
+        readTextFile,
+      }),
+    ).toBe("0123456789abcdef0123456789abcdef01234567");
+    expect(readTextFile).not.toHaveBeenCalled();
+  });
+
+  it("reads the deployment marker when no environment commit is set", () => {
+    expect(
+      readBuildCommit({
+        environmentCommit: null,
+        buildCommitPath: "/app/.paperclip-build-commit",
+        readTextFile: (path) => {
+          expect(path).toBe("/app/.paperclip-build-commit");
+          return "0123456789abcdef0123456789abcdef01234567\n";
+        },
+      }),
+    ).toBe("0123456789abcdef0123456789abcdef01234567");
+  });
+});
diff --git a/server/src/__tests__/server-info.test.ts b/server/src/__tests__/server-info.test.ts
index 1af391d431..89f6667583 100644
--- a/server/src/__tests__/server-info.test.ts
+++ b/server/src/__tests__/server-info.test.ts
@@ -129,6 +129,7 @@ describe("server info snapshot", () => {
       gitCommand: () => {
         throw new Error("fatal: not a git repository");
       },
+      buildCommitCommand: () => null,
     });
 
     expect(snapshot).toEqual({
@@ -139,6 +140,32 @@ describe("server info snapshot", () => {
       },
     });
   });
+
+  it("uses deployment commit metadata when the runtime has no git directory", () => {
+    const snapshot = createServerInfoSnapshot({
+      now: new Date("2026-06-26T00:00:00.000Z"),
+      gitCommand: () => {
+        throw new Error("fatal: not a git repository");
+      },
+      buildCommitCommand: () => "0123456789abcdef0123456789abcdef01234567",
+    });
+
+    expect(snapshot).toEqual({
+      processStartedAt: "2026-06-26T00:00:00.000Z",
+      git: {
+        available: true,
+        fullSha: "0123456789abcdef0123456789abcdef01234567",
+        shortSha: "0123456",
+        branchName: null,
+        subject: "Source build",
+        committedAt: null,
+        localChanges: {
+          available: false,
+          unavailableReason: "git_status_unavailable",
+        },
+      },
+    });
+  });
 });
 
 describe("getServerInfoSnapshot", () => {
diff --git a/server/src/__tests__/version.test.ts b/server/src/__tests__/version.test.ts
index cd660a3990..d6d717d8e6 100644
--- a/server/src/__tests__/version.test.ts
+++ b/server/src/__tests__/version.test.ts
@@ -40,6 +40,28 @@ describe("resolveServerVersion", () => {
     ).toBe("2026.626.0+58.git.518fc71ce");
   });
 
+  it("keeps the package version when git describe output is unparseable", () => {
+    expect(
+      resolveServerVersion({
+        buildCommit: "0123456789abcdef0123456789abcdef01234567",
+        packageVersion: "2026.706.0",
+        gitDescribeCommand: () => "canary/v2026.706.0-canary.1",
+        debugLog: vi.fn(),
+      }),
+    ).toBe("2026.706.0");
+  });
+
+  it("keeps the formal version for an exact release tag even when build metadata exists", () => {
+    expect(
+      resolveServerVersion({
+        buildCommit: "0123456789abcdef0123456789abcdef01234567",
+        packageVersion: "2026.706.0",
+        gitDescribeCommand: () => "v2026.706.0-0-g012345678\n",
+        debugLog: vi.fn(),
+      }),
+    ).toBe("2026.706.0");
+  });
+
   it("falls back to package version without throwing when git is unavailable", () => {
     const debugLog = vi.fn();
     const cause = new Error("spawn git ENOENT");
@@ -52,6 +74,7 @@ describe("resolveServerVersion", () => {
 
     expect(
       resolveServerVersion({
+        buildCommit: null,
         packageVersion: "2026.706.0",
         gitDescribeCommand: () => {
           throw err;
@@ -75,11 +98,25 @@ describe("resolveServerVersion", () => {
     );
   });
 
+  it("uses deployment commit metadata when a source build has no git directory", () => {
+    expect(
+      resolveServerVersion({
+        buildCommit: "0123456789abcdef0123456789abcdef01234567",
+        packageVersion: "2026.706.0",
+        gitDescribeCommand: () => {
+          throw new Error("fatal: not a git repository");
+        },
+        debugLog: vi.fn(),
+      }),
+    ).toBe("2026.706.0+0.git.0123456");
+  });
+
   it("skips git metadata probing for packaged installs under node_modules", () => {
     const debugLog = vi.fn();
 
     expect(
       resolveServerVersion({
+        buildCommit: "0123456789abcdef0123456789abcdef01234567",
         packageVersion: "2026.707.0-canary.12",
         debugLog,
         packageRoot: "/tmp/npm/_npx/example/node_modules/@paperclipai/server",
@@ -98,6 +135,7 @@ describe("resolveServerVersion", () => {
 
     expect(
       resolveServerVersion({
+        buildCommit: null,
         packageVersion: "2026.707.0-canary.12",
         debugLog,
         gitDescribeCommand,
@@ -119,6 +157,7 @@ describe("resolveServerVersion", () => {
     try {
       expect(
         resolveServerVersion({
+          buildCommit: null,
           packageVersion: "2026.706.0",
           gitDescribeCommand: () => {
             throw new Error("fatal: not a git repository");
diff --git a/server/src/build-commit.ts b/server/src/build-commit.ts
new file mode 100644
index 0000000000..105c6d590c
--- /dev/null
+++ b/server/src/build-commit.ts
@@ -0,0 +1,36 @@
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+
+type ReadTextFile = (path: string) => string;
+
+const FULL_SHA_RE = /^[0-9a-f]{40}$/i;
+const DEFAULT_BUILD_COMMIT_PATH = fileURLToPath(
+  new URL("../../.paperclip-build-commit", import.meta.url),
+);
+
+export function parseBuildCommit(value: string | null | undefined): string | null {
+  const commit = value?.trim() ?? "";
+  return FULL_SHA_RE.test(commit) ? commit.toLowerCase() : null;
+}
+
+export function readBuildCommit(
+  opts: {
+    environmentCommit?: string | null;
+    buildCommitPath?: string;
+    readTextFile?: ReadTextFile;
+  } = {},
+): string | null {
+  const environmentCommit = parseBuildCommit(
+    opts.environmentCommit === undefined
+      ? process.env.PAPERCLIP_BUILD_COMMIT
+      : opts.environmentCommit,
+  );
+  if (environmentCommit) return environmentCommit;
+
+  try {
+    const readTextFile = opts.readTextFile ?? ((path: string) => readFileSync(path, "utf8"));
+    return parseBuildCommit(readTextFile(opts.buildCommitPath ?? DEFAULT_BUILD_COMMIT_PATH));
+  } catch {
+    return null;
+  }
+}
diff --git a/server/src/server-info.ts b/server/src/server-info.ts
index eb386be6c3..455e622c87 100644
--- a/server/src/server-info.ts
+++ b/server/src/server-info.ts
@@ -1,11 +1,12 @@
 import { execFileSync } from "node:child_process";
 import type { ServerGitInfo, ServerGitLocalChanges, ServerInfoSnapshot } from "@paperclipai/shared";
+import { parseBuildCommit, readBuildCommit } from "./build-commit.js";
 
 export type { ServerGitInfo, ServerInfoSnapshot };
 
 type GitCommand = () => string;
+type BuildCommitCommand = () => string | null;
 
-const FULL_SHA_RE = /^[0-9a-f]{40}$/i;
 const SHORT_SHA_RE = /^[0-9a-f]{7,40}$/i;
 
 function defaultGitCommand() {
@@ -87,15 +88,16 @@ function parseGitInfo(
   const [fullSha = "", shortSha = "", subject = "", committedAt = ""] = output
     .trimEnd()
     .split("\n");
+  const parsedFullSha = parseBuildCommit(fullSha);
   const committedAtTime = Date.parse(committedAt);
 
-  if (!FULL_SHA_RE.test(fullSha) || !SHORT_SHA_RE.test(shortSha)) {
+  if (!parsedFullSha || !SHORT_SHA_RE.test(shortSha)) {
     return { available: false, unavailableReason: "invalid_git_metadata" };
   }
 
   return {
     available: true,
-    fullSha,
+    fullSha: parsedFullSha,
     shortSha,
     branchName,
     subject: subject.trim() || "No commit subject",
@@ -108,6 +110,7 @@ function readGitInfo(
   gitCommand: GitCommand = defaultGitCommand,
   gitStatusCommand: GitCommand = defaultGitStatusCommand,
   gitBranchCommand: GitCommand = defaultGitBranchCommand,
+  buildCommitCommand: BuildCommitCommand = readBuildCommit,
 ): ServerGitInfo {
   try {
     const output = gitCommand();
@@ -120,16 +123,43 @@ function readGitInfo(
     }
     return parseGitInfo(output, branchName, localChanges);
   } catch {
-    return { available: false, unavailableReason: "git_unavailable" };
+    const buildCommit = parseBuildCommit(buildCommitCommand());
+    if (!buildCommit) {
+      return { available: false, unavailableReason: "git_unavailable" };
+    }
+
+    return {
+      available: true,
+      fullSha: buildCommit,
+      shortSha: buildCommit.slice(0, 7),
+      branchName: null,
+      subject: "Source build",
+      committedAt: null,
+      localChanges: {
+        available: false,
+        unavailableReason: "git_status_unavailable",
+      },
+    };
   }
 }
 
 export function createServerInfoSnapshot(
-  opts: { now?: Date; gitCommand?: GitCommand; gitStatusCommand?: GitCommand; gitBranchCommand?: GitCommand } = {},
+  opts: {
+    now?: Date;
+    gitCommand?: GitCommand;
+    gitStatusCommand?: GitCommand;
+    gitBranchCommand?: GitCommand;
+    buildCommitCommand?: BuildCommitCommand;
+  } = {},
 ): ServerInfoSnapshot {
   return {
     processStartedAt: (opts.now ?? new Date()).toISOString(),
-    git: readGitInfo(opts.gitCommand, opts.gitStatusCommand, opts.gitBranchCommand),
+    git: readGitInfo(
+      opts.gitCommand,
+      opts.gitStatusCommand,
+      opts.gitBranchCommand,
+      opts.buildCommitCommand,
+    ),
   };
 }
 
@@ -143,12 +173,23 @@ const processStartedAt = new Date().toISOString();
 let gitInfoCache: { value: ServerGitInfo; expiresAt: number } | null = null;
 
 export function getServerInfoSnapshot(
-  opts: { now?: number; gitCommand?: GitCommand; gitStatusCommand?: GitCommand; gitBranchCommand?: GitCommand } = {},
+  opts: {
+    now?: number;
+    gitCommand?: GitCommand;
+    gitStatusCommand?: GitCommand;
+    gitBranchCommand?: GitCommand;
+    buildCommitCommand?: BuildCommitCommand;
+  } = {},
 ): ServerInfoSnapshot {
   const now = opts.now ?? Date.now();
   if (!gitInfoCache || now >= gitInfoCache.expiresAt) {
     gitInfoCache = {
-      value: readGitInfo(opts.gitCommand, opts.gitStatusCommand, opts.gitBranchCommand),
+      value: readGitInfo(
+        opts.gitCommand,
+        opts.gitStatusCommand,
+        opts.gitBranchCommand,
+        opts.buildCommitCommand,
+      ),
       expiresAt: now + GIT_INFO_CACHE_TTL_MS,
     };
   }
diff --git a/server/src/version.ts b/server/src/version.ts
index e543b79e1d..525c2e2697 100644
--- a/server/src/version.ts
+++ b/server/src/version.ts
@@ -2,6 +2,7 @@ import { createRequire } from "node:module";
 import { execFileSync } from "node:child_process";
 import { existsSync, realpathSync } from "node:fs";
 import { basename, dirname, join } from "node:path";
+import { parseBuildCommit, readBuildCommit } from "./build-commit.js";
 
 type PackageJson = {
   version?: string;
@@ -147,6 +148,7 @@ export function parseGitDescribeVersion(output: string): string | null {
 
 export function resolveServerVersion(
   opts: {
+    buildCommit?: string | null;
     gitDescribeCommand?: GitDescribeCommand;
     packageVersion?: string;
     debugLog?: DebugLog;
@@ -181,6 +183,7 @@ export function resolveServerVersion(
       { reason: "invalid_git_describe" },
       "falling back to package version for server version",
     );
+    return packageVersion;
   } catch (err) {
     debugLog(
       { err: summarizeError(err), reason: "git_describe_unavailable" },
@@ -188,6 +191,14 @@ export function resolveServerVersion(
     );
   }
 
+  const buildCommit =
+    opts.buildCommit === undefined
+      ? readBuildCommit()
+      : parseBuildCommit(opts.buildCommit);
+  if (buildCommit) {
+    return `${packageVersion}+0.git.${buildCommit.slice(0, 7)}`;
+  }
+
   return packageVersion;
 }