Allow Sandbox container limits overrides

Makefile

@@ -35,12 +35,19 @@ STATE_DIR    := $(HOME)/.local/state/opencode
 # it fails fast rather than thrashing. Sized to leave ~1 GiB / 2 CPUs of
 # headroom below the VM's own allocation for the VM/podman/gvproxy itself --
 # adjust alongside `podman machine set` if you resize the machine again.
+# Override any of these per-invocation by exporting OPENCODE_SANDBOX_MEMORY,
+# OPENCODE_SANDBOX_MEMORY_SWAP, and/or OPENCODE_SANDBOX_CPUS before running
+# `make opencode`/`make shell`.
+OPENCODE_SANDBOX_MEMORY      ?= 3072m
+OPENCODE_SANDBOX_MEMORY_SWAP ?= 3072m
+OPENCODE_SANDBOX_CPUS        ?= 4
+
 RUN_FLAGS := \
 	--rm -it \
 	--userns=keep-id \
-	--memory=3072m \
-	--memory-swap=3072m \
-	--cpus=4 \
+	--memory=$(OPENCODE_SANDBOX_MEMORY) \
+	--memory-swap=$(OPENCODE_SANDBOX_MEMORY_SWAP) \
+	--cpus=$(OPENCODE_SANDBOX_CPUS) \
 	--network $(NETWORK_NAME) \
 	--network-alias $(WORKDIR_NAME) \
 	-v $(CURDIR):/workspace \

README.md

@@ -86,7 +86,7 @@ Bumping a pinned LSP version means editing the corresponding `ARG`/`FROM` tag in
   Because these are real host paths shared by every container regardless of workdir, logging into OpenCode once carries over to every project you use the sandbox in.
 
 - Both run targets join a shared, auto-created Podman network (`opencode-sandbox-net`) under a `--network-alias` derived from the current directory's name, so a container started from another dev-container setup on the same network can reach this one by that name (and vice versa).
-- Both run targets also cap the container to `--memory=3072m --memory-swap=3072m --cpus=4`. Without this, a heavy JVM build tool (Gradle's daemon plus its separate Kotlin-compiler daemon are the worst offenders — both auto-size their heap off "available" memory with no idea they're sharing a fixed-size VM) can consume the entire `podman machine`'s RAM. That starves the VM's own guest kernel, which stalls the processes Podman itself needs to stay responsive — so the *whole machine* hangs, not just the container. The cap forces a contained OOM kill instead. Sized to leave headroom below the VM's own allocation for the VM/podman/gvproxy itself — adjust both together if you resize the machine (`podman machine set --memory <MB> --cpus <N> podman-machine-default`, machine must be stopped first). The `Containerfile` also sets a default `GRADLE_OPTS=-Xmx1024m` so the Gradle daemon itself doesn't try to claim the whole container ceiling; a project whose Kotlin-compiler daemon also needs bounding should set `kotlin.daemon.jvmargs` in its own `gradle.properties`.
+- Both run targets also cap the container to `--memory=3072m --memory-swap=3072m --cpus=4`. Without this, a heavy JVM build tool (Gradle's daemon plus its separate Kotlin-compiler daemon are the worst offenders — both auto-size their heap off "available" memory with no idea they're sharing a fixed-size VM) can consume the entire `podman machine`'s RAM. That starves the VM's own guest kernel, which stalls the processes Podman itself needs to stay responsive — so the *whole machine* hangs, not just the container. The cap forces a contained OOM kill instead. Sized to leave headroom below the VM's own allocation for the VM/podman/gvproxy itself — adjust both together if you resize the machine (`podman machine set --memory <MB> --cpus <N> podman-machine-default`, machine must be stopped first). The `Containerfile` also sets a default `GRADLE_OPTS=-Xmx1024m` so the Gradle daemon itself doesn't try to claim the whole container ceiling; a project whose Kotlin-compiler daemon also needs bounding should set `kotlin.daemon.jvmargs` in its own `gradle.properties`. These defaults can be overridden per-invocation by exporting `OPENCODE_SANDBOX_MEMORY`, `OPENCODE_SANDBOX_MEMORY_SWAP`, and/or `OPENCODE_SANDBOX_CPUS` before running `make opencode`/`make shell` (e.g. `OPENCODE_SANDBOX_MEMORY=4096m OPENCODE_SANDBOX_CPUS=6 make shell`).
 
 ## macOS-specific notes