diff --git a/script/build-project-images b/script/build-project-images
new file mode 100755
index 00000000..7b8a53fe
--- /dev/null
+++ b/script/build-project-images
@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Build all project images in dependency order:
+#   huskies  →  huskies-project-base  →  huskies-project-<stack> (one per stack fragment)
+#
+# Run this after `script/docker_rebuild` or whenever you add a new stack.
+# Safe to re-run: each step re-tags the image with the latest layers.
+
+cd "$(dirname "$0")/.."
+
+if [[ -f .env ]]; then
+    set -a
+    source .env
+    set +a
+fi
+
+CACHE_FLAG=""
+if [[ "${1:-}" == "--no-cache" ]]; then
+    CACHE_FLAG="--no-cache"
+fi
+
+echo "==> Building huskies"
+docker build $CACHE_FLAG -t huskies -f docker/Dockerfile .
+
+echo "==> Building huskies-project-base"
+docker build $CACHE_FLAG -t huskies-project-base -f docker/Dockerfile.base .
+
+for fragment in docker/stacks/*/Dockerfile.fragment; do
+    stack=$(basename "$(dirname "$fragment")")
+    image="huskies-project-${stack}"
+    echo "==> Building ${image}"
+    (printf 'FROM huskies-project-base\n'; cat "$fragment") \
+        | docker build $CACHE_FLAG -t "$image" -
+done
+
+echo "All project images built."
diff --git a/script/docker_rebuild b/script/docker_rebuild
index 876c85a8..280cebca 100755
--- a/script/docker_rebuild
+++ b/script/docker_rebuild
@@ -24,4 +24,6 @@ docker compose -f docker/docker-compose.yml down
 docker compose -f docker/docker-compose.yml build $CACHE_FLAG
 docker compose -f docker/docker-compose.yml up -d
 
+script/build-project-images $CACHE_FLAG
+
 echo "Rebuild complete. Logs: docker compose -f docker/docker-compose.yml logs -f"
diff --git a/server/src/chat/transport/matrix/new_project.rs b/server/src/chat/transport/matrix/new_project.rs
index b85a84e1..27569de4 100644
--- a/server/src/chat/transport/matrix/new_project.rs
+++ b/server/src/chat/transport/matrix/new_project.rs
@@ -518,7 +518,7 @@ async fn handle_adopt_project(
         Ok(out) => {
             let stderr = String::from_utf8_lossy(&out.stderr);
             let _ = tokio::fs::remove_dir_all(&ssh_key_dir).await;
-            format!("Docker container launch failed: {}", stderr.trim())
+            interpret_docker_run_error(&stderr, &image)
         }
         Err(e) => {
             let _ = tokio::fs::remove_dir_all(&ssh_key_dir).await;
@@ -891,9 +891,9 @@ pub async fn handle_new_project(
             let stderr = String::from_utf8_lossy(&out.stderr);
             let _ = tokio::fs::remove_dir_all(&host_path).await;
             let _ = tokio::fs::remove_dir_all(&ssh_key_dir).await;
+            let base_msg = interpret_docker_run_error(&stderr, &image);
             format!(
-                "Docker container launch failed: {}\n\nPartial state removed at `{}`.",
-                stderr.trim(),
+                "{base_msg}\n\nPartial state removed at `{}`.",
                 host_path.display()
             )
         }
@@ -908,6 +908,22 @@ pub async fn handle_new_project(
     }
 }
 
+/// Convert a failed `docker run` stderr into an actionable chat message.
+///
+/// When Docker cannot find the image locally it prints `Unable to find image`.
+/// That bare error is unhelpful — this function maps it to a message that tells
+/// the user which script to run.  All other failures are passed through as-is.
+fn interpret_docker_run_error(stderr: &str, image: &str) -> String {
+    if stderr.contains("Unable to find image") {
+        format!(
+            "Image `{image}` not found locally. \
+             Build project images first by running `script/build-project-images`."
+        )
+    } else {
+        format!("Docker container launch failed: {}", stderr.trim())
+    }
+}
+
 /// Find a free TCP port by attempting to bind starting from `start`.
 ///
 /// Scans up to 100 ports above `start` and returns the first available one.
@@ -1257,6 +1273,37 @@ mod tests {
         assert!(warnings.is_empty());
     }
 
+    // ── Missing-image error path ─────────────────────────────────────────────
+
+    #[test]
+    fn interpret_docker_run_error_missing_image_points_at_script() {
+        let stderr = "Unable to find image 'huskies-project-rust:latest' locally\n\
+                      docker: Error response from daemon: pull access denied";
+        let msg = interpret_docker_run_error(stderr, "huskies-project-rust");
+        assert!(
+            msg.contains("script/build-project-images"),
+            "expected script name in error message, got: {msg}"
+        );
+        assert!(
+            msg.contains("huskies-project-rust"),
+            "expected image name in error message, got: {msg}"
+        );
+    }
+
+    #[test]
+    fn interpret_docker_run_error_other_failure_passes_through() {
+        let stderr = "Error response from daemon: container name already in use";
+        let msg = interpret_docker_run_error(stderr, "huskies-project-rust");
+        assert!(
+            msg.contains("Docker container launch failed"),
+            "expected generic error message, got: {msg}"
+        );
+        assert!(
+            msg.contains("container name already in use"),
+            "expected original stderr in message, got: {msg}"
+        );
+    }
+
     #[test]
     fn detect_stack_jvm_build_gradle_kts() {
         let dir = tempfile::tempdir().unwrap();