feat: container-only mode with Go pre-installed (no fallback)

- Container mode is always ON (like herm), --no-container to opt out
- Image includes Go 1.26.1, Python 3, Node.js, git, ripgrep, make, gcc
- No fallback to host — if Docker is not running, shows clear error
- DevEnv tool available for agent to extend environment on-the-fly

Author: Patel230

cmd/container_boot.go

@@ -26,11 +26,19 @@ type containerStatusMsg struct {
 // It writes the Dockerfile to a temp dir and runs docker build.
 func buildHawkImage(ctx context.Context, tag string) bool {
 	dockerfile := `FROM ubuntu:24.04
+ENV DEBIAN_FRONTEND=noninteractive
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    git curl wget jq tree ripgrep fd-find make gcc \
-    python3 python3-pip nodejs npm ca-certificates openssh-client \
+    git curl wget jq tree ripgrep fd-find make gcc g++ \
+    python3 python3-pip python3-venv \
+    nodejs npm \
+    ca-certificates openssh-client unzip xz-utils \
     && rm -rf /var/lib/apt/lists/* \
     && ln -sf /usr/bin/fdfind /usr/bin/fd
+# Install Go
+RUN curl -fsSL https://go.dev/dl/go1.26.1.linux-$(dpkg --print-architecture).tar.gz | tar -C /usr/local -xz
+ENV PATH="/usr/local/go/bin:${PATH}"
+ENV GOPATH="/root/go"
+ENV PATH="${GOPATH}/bin:${PATH}"
 ENV TERM=xterm-256color LANG=C.UTF-8
 `
 	// Use platform-appropriate arch
@@ -57,16 +65,13 @@ ENV TERM=xterm-256color LANG=C.UTF-8
 }
 
 // shouldUseContainer determines if hawk should run in container mode.
-// Default: YES if Docker is available (like herm). User can override with --no-container.
+// Default: ALWAYS (like herm). Container-first, no fallback.
+// User can opt out with --no-container for host mode.
 func shouldUseContainer() bool {
 	if noContainer {
 		return false
 	}
-	if containerMode {
-		return true
-	}
-	// Default: auto-detect. If Docker is running, use container mode.
-	return sandbox.DockerAvailable()
+	return true
 }
 
 // bootContainerCmd starts the container in the background and sends status

container/Dockerfile

@@ -1,28 +1,21 @@
 FROM ubuntu:24.04
 
+ENV DEBIAN_FRONTEND=noninteractive
+
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    git \
-    curl \
-    wget \
-    jq \
-    tree \
-    ripgrep \
-    fd-find \
-    make \
-    gcc \
-    python3 \
-    python3-pip \
-    nodejs \
-    npm \
-    ca-certificates \
-    openssh-client \
-    && rm -rf /var/lib/apt/lists/*
+    git curl wget jq tree ripgrep fd-find make gcc g++ \
+    python3 python3-pip python3-venv \
+    nodejs npm \
+    ca-certificates openssh-client unzip xz-utils \
+    && rm -rf /var/lib/apt/lists/* \
+    && ln -sf /usr/bin/fdfind /usr/bin/fd
 
-# Create symlinks for common tool names
-RUN ln -sf /usr/bin/fdfind /usr/bin/fd
+# Install Go
+RUN curl -fsSL https://go.dev/dl/go1.26.1.linux-$(dpkg --print-architecture).tar.gz \
+    | tar -C /usr/local -xz
 
-# Set reasonable defaults
+ENV PATH="/usr/local/go/bin:${PATH}"
+ENV GOPATH="/root/go"
+ENV PATH="${GOPATH}/bin:${PATH}"
 ENV TERM=xterm-256color
 ENV LANG=C.UTF-8
-
-WORKDIR /workspace