diff --git a/.dockerignore b/.dockerignore
new file mode 100644
index 00000000000..e79a88e890e
--- /dev/null
+++ b/.dockerignore
@@ -0,0 +1,17 @@
+# Git history - not needed in build context
+.git
+
+# Root node_modules - reinstalled inside container via npm ci
+node_modules
+
+# Package-level node_modules - reinstalled inside container
+packages/*/node_modules
+
+# Development and IDE files
+.github
+.vscode
+npm-debug.log*
+
+# Misc
+.DS_Store
+*.tmp
diff --git a/Dockerfile b/Dockerfile
index 44ba3439023..31d9c6d4460 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,3 +1,44 @@
+# ---- Stage 1: Builder ----
+FROM docker.io/library/node:20-slim AS builder
+
+# Install git (needed by generate-git-commit-info.js script)
+RUN apt-get update && apt-get install -y --no-install-recommends git \
+  && apt-get clean && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /build
+
+# Copy only package.json files first for better layer caching
+# Dependencies only re-install when package files change, not source files
+COPY package*.json ./
+COPY packages/cli/package*.json ./packages/cli/
+COPY packages/core/package*.json ./packages/core/
+COPY packages/vscode-ide-companion/package*.json ./packages/vscode-ide-companion/
+COPY packages/vscode-ide-companion/scripts/ ./packages/vscode-ide-companion/scripts/
+COPY packages/devtools/package*.json ./packages/devtools/
+COPY packages/sdk/package*.json ./packages/sdk/
+COPY packages/test-utils/package*.json ./packages/test-utils/
+COPY packages/a2a-server/package*.json ./packages/a2a-server/
+
+# Use npm ci for consistent, reliable builds (respects package-lock.json)
+RUN HUSKY=0 npm ci --ignore-scripts
+
+# Now copy the rest of the source (after install for better caching)
+COPY packages/ ./packages/
+COPY tsconfig*.json ./
+COPY eslint.config.js ./
+COPY scripts/ ./scripts/
+COPY esbuild.config.js ./
+
+# Pass git commit hash as build arg instead of copying entire .git directory
+ARG GIT_COMMIT=unknown
+ENV GIT_COMMIT=$GIT_COMMIT
+
+# Build and pack artifacts
+RUN HUSKY=0 npm run build && \
+    npm pack -w packages/core --pack-destination packages/core/dist/ && \
+    npm pack -w packages/cli --pack-destination packages/cli/dist/
+
+# ---- Stage 2: Runtime ----
 FROM docker.io/library/node:20-slim
 
 ARG SANDBOX_NAME="gemini-cli-sandbox"
@@ -50,4 +91,4 @@ RUN npm install -g /tmp/gemini-core.tgz \
   && rm -f /tmp/gemini-{cli,core}.tgz
 
 # default entrypoint when none specified
-CMD ["gemini"]
+ENTRYPOINT ["/usr/local/share/npm-global/bin/gemini"]
\ No newline at end of file
diff --git a/scripts/generate-git-commit-info.js b/scripts/generate-git-commit-info.js
index 049c39c249b..8aafbf54112 100644
--- a/scripts/generate-git-commit-info.js
+++ b/scripts/generate-git-commit-info.js
@@ -42,13 +42,19 @@ if (!existsSync(generatedCoreDir)) {
 }
 
 try {
-  const gitHash = execSync('git rev-parse --short HEAD', {
-    encoding: 'utf-8',
-  }).trim();
-  if (gitHash) {
-    gitCommitInfo = gitHash;
+  // Check for GIT_COMMIT env var first (e.g. when building inside Docker
+  // without a .git directory available)
+  const envCommit = process.env.GIT_COMMIT;
+  if (envCommit && /^[0-9a-f]+$/i.test(envCommit)) {
+    gitCommitInfo = envCommit;
+  } else {
+    const gitHash = execSync('git rev-parse --short HEAD', {
+      encoding: 'utf-8',
+    }).trim();
+    if (gitHash) {
+      gitCommitInfo = gitHash;
+    }
   }
-
   const result = await readPackageUp();
   cliVersion = result?.packageJson?.version ?? 'UNKNOWN';
 } catch {