fix: prevent arm64 OOM during linking with lld + job limit

.cargo/config.toml

@@ -3,3 +3,13 @@ incremental = true
 
 [target.x86_64-pc-windows-msvc]
 rustflags = ["-Ctarget-feature=+crt-static"]
+
+# Use lld linker on Linux — significantly less memory than default ld,
+# critical for arm64 builds on 16GB Graviton runners.
+[target.x86_64-unknown-linux-gnu]
+linker = "clang"
+rustflags = ["-Clink-arg=-fuse-ld=lld"]
+
+[target.aarch64-unknown-linux-gnu]
+linker = "clang"
+rustflags = ["-Clink-arg=-fuse-ld=lld"]

.github/Dockerfile

@@ -1,7 +1,7 @@
 # Use a Rust base image
 FROM rust:bookworm AS builder
 ARG BUILD_TYPE
-RUN apt-get update && apt-get install -y libclang-dev cmake libssl-dev libc++-dev libc++abi-dev lld
+RUN apt-get update && apt-get install -y clang libclang-dev cmake libssl-dev libc++-dev libc++abi-dev lld
 
 # Install nvm, npm and node
 RUN rm /bin/sh && ln -s /bin/bash /bin/sh
@@ -36,6 +36,10 @@ COPY . .
 RUN rustup default 1.88
 RUN rustup component add rustfmt
 
+# Limit parallel jobs to prevent OOM on arm64 (16GB Graviton).
+# lld linker configured in .cargo/config.toml (uses ~3x less RAM than ld).
+ENV CARGO_BUILD_JOBS=4
+
 # Build main code, pre-compile tests, and cleanup in SINGLE layer
 # This is critical - separate RUN commands create Docker layers that preserve old data
 # Even if we delete files in a later layer, the image size includes all layers

docker/Dockerfile

@@ -25,6 +25,7 @@ ARG VCS_REF
 
 # Install build dependencies
 RUN apt-get update && apt-get install -y \
+    clang \
     libclang-dev \
     cmake \
     libssl-dev \
@@ -43,6 +44,10 @@ COPY . .
 # Add rustfmt for build
 RUN rustup component add rustfmt
 
+# Limit parallel codegen/linker jobs to prevent OOM on arm64 (16GB Graviton).
+# lld is configured as the linker via .cargo/config.toml (uses ~3x less RAM than ld).
+ENV CARGO_BUILD_JOBS=4
+
 # Build the project
 # Build the entire workspace to properly resolve all dependencies
 # Then extract just the hanzo_node binary we need