opencode-lowmem
The same agent, bounded memory. Built after a real workday ended with 50+ finished subagent tabs that nothing ever freed and a process past 12 GB RSS — the same workload now runs at ~1 GB. Nothing is removed or gated: every change bounds a resource or fixes a reliability defect.
The database format is untouched — sessions, auth, and config work interchangeably with stock opencode. Plugins work unchanged too: this fork is built and dogfooded daily with the oh-my-openagent plugin toolkit.
Why this fork exists
One heavy delegation day: 50+ finished subagent tabs sitting in the UI forever, a process that had crept past 12 GB on a 28 GB machine, and a swap partition doing overtime. The stale tabs were the visible symptom — underneath, every compaction re-materialized full session histories, text deltas accumulated quadratically, multi-megabyte diff patches rode every update event, and finished streams kept their listeners alive.
The fixes already existed as unmerged upstream PRs, plus a few small bounds-oriented patches nobody had written yet. This fork ships all of them — and keeps the newest 50 finished agents in the list instead of every one ever spawned. Same machine, same day, same workload: stock build ~12 GB after hours; this fork ~1 GB.
What's in the fork
Ported upstream fixes (never merged upstream)
| Fix | Plain language | Detail |
|---|---|---|
| Bounded compacted-history hydration | After context compaction, only the recent window loads; old history stays on disk until needed | #39930 — a 609-message session materialized 11 MB; now ~0.8 MB |
| O(N) delta accumulation | Very long replies no longer get slower the longer they run | #42150 — text/reasoning deltas were O(N²) string concatenation |
| PubSub listener leak fix | Subscriptions to finished streams are released | #38939 — allBounded kept listeners alive forever |
| Config cache isolation | Two projects open at once can't corrupt each other's settings | #41950 — global config cache mutated across workspaces |
| Empty-stream retry | A gateway that closes cleanly with no content retries instead of silently ending your turn | #43881 — finishReason: unknown + 0 output tokens raises a retryable error (adds a regression test) |
| Stream failures marked errored | Failed streams are recorded as errored, not as normal stops | #42176 — error path sets finish: "error" |
| Honest SSE chunk timeout | Server keepalive comments can't fake "data is flowing" during a stall | #43607 — one deadline per stream, reset only on complete data: events |
Original fork work (customs)
| Feature | Plain language | Detail |
|---|---|---|
| Diff-patch caps | Snapshots of large edits can't balloon memory and disk | per-patch 100 KB, 256 KB aggregate; summaries store metadata and recompute on read |
| Subagent tab eviction | The subagent list keeps the newest 50 finished agents, not every one ever spawned | running, pinned, and permission-holding sessions are exempt; evicted agents revive if they ask again; 256-entry revival memory |
| Conveyor ordering | Finished subagents stack oldest-first — the bottom of the list is always the latest | deterministic even for same-millisecond session IDs |
| Conveyor navigation | Tab/arrows move through child sessions in creation order; footer and session list finally agree | shared comparator with a causal same-millisecond tie-break |
| Git subcommand classifier | "Always allow" for git -C ../worktree commit stores git commit * — never junk, never a wider grant than you approved |
env/command unwrapping + git global-option skipping + scoped patterns |
Provenance, per-round history, the durability/rebase policy, and the deliberately-not-ported list: PORTS.md.
Install
One-liner (prebuilt binaries from GitHub Releases)
curl -fsSL https://raw.githubusercontent.com/renekris/opencode-lowmem/lowmem/scripts/fork-install.sh | bashDetects your platform, downloads the matching release binary, installs to
~/.opencode/bin/opencode. Running sessions are never killed; new sessions pick
up the new build.
Build from source
Requires bun:
git clone https://github.com/renekris/opencode-lowmem
cd opencode-lowmem
./scripts/fork-build.shBuilds all platform targets, stamps the version (<upstream>-lowmem.<round>
from git tags), smoke-tests, and tags the build.
External tool installers
- npm: not yet published. Upstream ships via npm with per-platform
optionalDependencies; the same packaging works under a fork package name
(
npm i -g opencode-lowmem) once an npm publishing setup exists. - Homebrew: not yet available. A
renekris/lowmemtap with formulas pointing at the release binaries is the natural next step. - Direct download: per-platform archives are attached to every release.
Updating from upstream
Rebase onto the new upstream tag. The port manifest (PORTS.md) lists exactly which seams to re-check, and behavior-pinning tests fail loudly if an upstream refactor moved a hunk. Fork upkeep procedure and rollback recipe: fork section of AGENTS.md.
Credit
All ported work is credited in PORTS.md and in each commit's
(port of upstream #NNNNN) trailer. Upstream authors did the hard diagnosis;
this fork just ships it.
About upstream
This fork builds on opencode — the open source AI coding agent. See the upstream README for everything not fork-specific.