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Show HN: Loomcycle – a sidecar runtime for AI agents (Go binary, Apache-2.0)

Loomcycle, an open-source sidecar runtime for AI agents, has reached v1.0 under the Apache-2.0 license. The Go binary provides a hardened agent loop, MCP support on both sides, multi-replica high availability, and runs alongside existing applications without requiring code changes. The release marks a stable, distribution-ready milestone after extensive hardening and testing.

read34 min views4 publishedJun 17, 2026

The agentic runtime, in a sidecar.

One Go binary alongside your application. Hardened agent loop, MCP on both sides, multi-replica HA. Apache-2.0.

🌐 loomcycle.dev · 📝

Engineering blog· 📐

Architecture

🌳

v1.0 is here.loomcycle1.0is released — the feature set is complete and the runtime is hardened and distribution-ready. The core primitives stabilised across the v0.8 → v0.23 line (multi-replica HA; the substrate Defs Agent/Skill/MCPServer/Schedule/Webhook/MemoryBackend/A2A; A2A interoperability; inbound webhooks; pluggable memory + a memory layer; the syntheticcode-js

provider; andOSS multi-tenant authorizationin v0.17.0 — per-principal bearer tokens + a role-aware Web UI). The v0.24 → v0.37 line was a hardening + operability run: the interactive terminal, /resume/snapshot + cross-instance resume, the context-compaction subsystem, context-transform plugins, external fan-out on every transport, and slow-local-model robustness. 1.0 itself is a pure hardening + distribution milestone — no new primitives — wired to Homebrew, multi-arch Docker, and the Claude Code plugin. 8-hour stability soak: 1.27M circuits, 3.8M agent runs, 100% completion across 468 waves, zero leaks. Apache-2.0. We welcome bug reports, security disclosures, feature contributions, downstream consumers, and forks. See[.]CONTRIBUTING.md

The agentic runtime, in a sidecar. loomcycle is one Go binary, ~50 MB. It runs alongside your application, not inside it. Your app calls loomcycle over HTTP, gRPC, MCP, the TypeScript adapter, or the Python adapter. The agent loop, multi-provider routing, memory and channel primitives, MCP server identity, OpenTelemetry traces, and multi-replica coordination all live in the binary. Your application stays in whatever language you wrote it in.

The shape that's different. Today's agentic-systems market gives you three options. One: embed a Python or TypeScript library inside your application process. Two: rent a managed cloud service tied to one vendor's IAM. Three: proxy your model calls through a gateway that doesn't actually run agents.

loomcycle is a fourth option. A lightweight self-hostable runtime that owns the loop and speaks every wire format your stack already uses.

Release Highlights
v0.4 → v0.26.x foundation
Everything the runtime is built on, condensed. Seven inference modes: Anthropic, OpenAI, DeepSeek, Gemini, Ollama (cloud + local), plus the synthetic provider and a mock provider. The hardened code-js model → tool_use → tool_result loop. 19 built-in tools with Claude Code parity (Read, Write, Edit, Grep, Glob, NotebookEdit), plus HTTP, WebFetch, WebSearch, Bash, Agent, Skill, Memory, Channel, AgentDef, SkillDef, Evaluation, Interruption, Context. The content-addressed, runtime-mutable substrate (Agent / Skill / MCPServer / Schedule / Webhook / MemoryBackend / A2A defs). Vector Memory (sqlite-vec / pgvector) on a pluggable MemoryBackend, with a memory layer above. MCP on both sides. The LLM Gateway + OpenAI-compatible shims. A2A interop. Input webhooks. Ensemble-sync primitives (RFC S). OTEL + per-tenant fairness + / Resume / Snapshot + multi-replica HA. Per-run named credentials + tool-use hooks. OSS multi-tenant authorization (RFC L, v0.17.0) across both the state and definition planes. The embedded React Web UI + the interactive terminal. TS + Python + n8n adapters. Homebrew + Docker distribution. Per-version detail:
REVISIONS.md
v0.27.0
Interactive runs survive leaving the terminal. Background-goroutine execution under context.WithoutCancel , re-attach via GET /v1/runs/{run_id}/stream (replay-from-?from_seq + live-tail). Context op=self reports the resolved provider + model.
v0.28.0
Per-agent LLM (temperature / top_p / top_k / penalties / seed / stop, set via yaml or AgentDef overlay or per-run). And sampling : the loop parks at an iteration boundary and `` cooperative quiesce() waits for in-flight runs, so a mid-run snapshot is reliable.
v0.29.0
Web UI + operability. Agent-editor sampling controls + a collapsible advanced JSON/YAML overlay, terminal message-echo + a context-size gauge, and soft reclaim of a retired agent name (no new runtime primitives).
v0.30.0
Cross-instance resume of a snapshotted mid-run (RFC X Phase 2). A d run is re-dispatched by reconstructing its loop from the transcript, fired after a snapshot restore and at boot (crash recovery, cluster-gated).
v0.31.0
Park + resume a fan-out parent blocked in Agent.parallel_spawn (RFC X Phase 3). -watcher + a no-schema-change spawn ledger, gated behind LOOMCYCLE_RESUME_FANOUT .
v0.32.0
Context-compaction subsystem. Replace older turns with a summary + keep-last-N verbatim (clean user-turn boundary, non-destructive). Manual / auto / self triggers and a per-agent compaction block that flows down the spawn tree.
v0.33.0
External fan-out and the run-mutation surface on every transport. POST /v1/runs:batch , a spawn_runs MCP tool (≤32 server-concurrent), a SpawnRunBatch RPC. compact_run / CompactRun . Per-run sampling + compaction on MCP/gRPC. @loomcycle/client 0.33.0.
v0.34.0
Context-transform plugins (RFC Z Phase 1a, with the redact outbound-secret-scrub plugin), an exp7 self-review hardening pass, and a cross-provider thinking-model fallback downgrade (reasonerchat ).
v0.34.1
Hardening + branding (no new features). A central tenant-scoping store accessor closing three live cross-tenant read gaps (security review S2), plus the new loomcycle brand logo and favicon in the Web UI.
v0.34.2
Web UI design system + theming. A tokenized --lc-* design system (spacing / type / radius / shadow / fonts + semantic colors), light + dark themes (OS default + a persistent topbar toggle), bundled brand fonts (Outfit / Inter / JetBrains Mono), and the loom-wood accent. Plus a loop fix (interactive runs unbounded by default; no more stop-at-16) and a #56c596 -race test de-flake.
v0.34.3
Patch. Context op=self reports a fresh context footprint right after a compaction. It had kept showing the stale pre-compaction size (e.g. 164k / 82% ) for one turn even though the wire request had already shrunk. The loop now refreshes lastCtxTokens at every compaction site.
v0.34.4
Patch. Interactive-terminal UX + local-model fixes: a collapsible interactive-sessions switcher on the run page (and interactive tags on the runs page), a flashing waiting indicator in the terminal, the Ollama context gauge backed by num_ctx , generous (300s), relative ollama-local timeoutssandbox paths anchored to the root (not the process cwd), and the static agent base re-surfaced in the Library when no dynamic version is active.
v0.34.5
Patch. Ollama now reports the model's actual loaded context window (read from /api/ps at the stream's done frame) instead of only a pinned num_ctx — so the gauge is truthful for local models loaded at the server's OLLAMA_CONTEXT_LENGTH ; plus docs (the architecture diagram + ARCHITECTURE.md show the context-transform plugin layer; a README v1.0 voice refresh).
v0.35.0
Model aliases in tier candidates. A models: alias (e.g. local-gemma ) now resolves anywhere a tier candidate is accepted — per-agent models: , user_tiers , and the library tiers: — not only in an agent pin, closing the "pin expands aliases but tier candidates don't" 503. A candidate can be written as a bare alias string (- local-gemma ); config-load validation and the Web UI Library editor know aliases too.
v0.36.0
Jailed agents can see their sandbox. The Read /Write /Edit /Bash path docs now instruct relative paths (they wrongly said "Absolute file path," so agents passed host paths that resolve outside the jail), and reports the sandbox roots (Context op=self read_root /write_root /bash_cwd ) + the effective host allowlist. Plus a collapsible left column on the run page so the live terminal can use the full width.
v0.37.0
Slow-local-model robustness. Two loop fixes that keep an interactive run on a slow local model alive for hours: a run-lifetime heartbeat (a long prefill / retry no longer gets reaped as a crashed run) and a compaction window cap (auto-compaction always fits the model's window instead of "succeeding" yet still overflowing). Plus an aliases-first loomcycle.example.yaml , a "Local models (Ollama)" config guide + a loomcycle.local-interactive.example.yaml . Validated by a 133-min standalone local run.
v1.0.0
🌳 1.0 — feature-complete, hardened, distribution-ready. The milestone the roadmap pointed at: no new primitives, the culmination of the v0.8→v0.37 primitive + hardening line. Apache-2.0, wired to Homebrew / multi-arch Docker / the Claude Code plugin. Same codebase as v0.37.0, tagged as the stable 1.0.

Full per-version log: REVISIONS.md.

Same Go binary, same config schema. Operator flips a few env vars to pick the posture.

Posture Configuration shape Use case
True managed sandbox
LOOMCYCLE_BASH_ENABLED=0 , LOOMCYCLE_READ_ROOT / LOOMCYCLE_WRITE_ROOT unset, LOOMCYCLE_HTTP_HOST_ALLOWLIST empty, LOOMCYCLE_HTTP_CALLER_AUTHORITATIVE=1 . Every tool default-deny; agents can only reach what the caller's per-request allowed_hosts says.
Shared-server deployments processing untrusted prompts. The runtime survives contact with adversarial input.
Agentic dev environment
Bash enabled, filesystem roots set to your workspace, broad allowed_hosts , optional local Ollama for offline work.
Local development. Internal trusted operators. Single-user research workstation.

The trust boundary is operator / caller. The operator config is the floor; callers can narrow per-request but never widen. The bearer token (LOOMCYCLE_AUTH_TOKEN

) is the authority. Treat anyone with the token as fully trusted to drive the runtime. For true isolation in the sandbox posture, run loomcycle inside a container or VM. Bash

is restricted (cwd, env scrub, output bounds, timeouts) but it is not a kernel-level sandbox.

Pick the path that fits. All four ship the same single static binary plus the v0.11.1 init

/ doctor

first-run flow. Context.help installation

covers each in detail.

brew install denn-gubsky/loomcycle/loomcycle

docker pull denngubsky/loomcycle:latest

go install github.com/denn-gubsky/loomcycle/cmd/loomcycle@latest

curl -L https://github.com/denn-gubsky/loomcycle/releases/latest/download/loomcycle-darwin-arm64.tar.gz | tar xz
loomcycle init --with-token   # writes config + mints a token to ~/.config/loomcycle/auth.env (0600)
export ANTHROPIC_API_KEY=sk-...   # (or OPENAI_API_KEY / DEEPSEEK_API_KEY) — at least one provider key
loomcycle doctor              # verify env + keys + storage + the just-minted token
loomcycle                     # starts on 127.0.0.1:8787 (auto-loads auth.env — no shell-rc edit)

init --with-token

prints the Web UI URL (http://127.0.0.1:8787/ui

). Open it, then paste the token from ~/.config/loomcycle/auth.env

at the login prompt. (The token is kept in the 0600

file and never embedded in a URL. A ?token=

link would leak the bearer into browser history and into any fronting proxy's logs.) loomcycle

and loomcycle doctor

both auto-load auth.env

from the config dir; a real export LOOMCYCLE_AUTH_TOKEN=…

always overrides it.

Pick the tier that fits. Each is a superset of the one above. Auth is enforced only once something is configured, so Tier 1 needs no token at all.

No token, no flags. Fastest way to kick the tires on 127.0.0.1

.

loomcycle init               # config only — no secret written
export ANTHROPIC_API_KEY=sk-...
loomcycle                    # open mode: /v1/* + /ui pass through unauthenticated (logs a warning)
open http://127.0.0.1:8787/ui

With no LOOMCYCLE_AUTH_TOKEN

and no minted tokens, the runtime runs open on localhost. Every request is allowed, whoami returns a synthetic admin. Good for a 10-second smoke test. Never expose this off localhost.

One bearer gates everything. init --with-token

is the easy button (above). Equivalent manual setup:

loomcycle init
export LOOMCYCLE_AUTH_TOKEN=$(openssl rand -hex 32)   # or: loomcycle init --with-token
export ANTHROPIC_API_KEY=sk-...
loomcycle
open "http://127.0.0.1:8787/ui?token=$LOOMCYCLE_AUTH_TOKEN"   # sets the cookie once

Treat anyone holding the token as fully trusted to drive the runtime.

Mint a distinct bearer per developer / app, each bound to an authoritative (tenant, subject, scopes)

. Migrate a Tier-2 deployment in place, no downtime:

loomcycle operator-token create --copy-from-env --name ops --tenant ops --scopes substrate:admin
loomcycle operator-token create --name acme-app --tenant acme --subject alice --scopes runs:create

The first admin OperatorTokenDef

disables the legacy shared-token fallback. Per-route HTTP and per-RPC gRPC scopes. The Web UI becomes role-aware (super-admin vs tenant). See Context.help operator-tokens

and the v0.17.0 notes in REVISIONS.md.

Smoke any tier:

curl http://127.0.0.1:8787/healthz

Real call (from another terminal):

curl -N http://127.0.0.1:8787/v1/runs \
  -H "Authorization: Bearer $LOOMCYCLE_AUTH_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"agent":"default","segments":[{"role":"user","content":[{"type":"trusted-text","text":"Hello"}]}]}'

Build from a checkout (for development):

make build-all       # UI + binary in one shot; output → ./bin/loomcycle
./bin/loomcycle --config loomcycle.example.yaml

Multi-replica cluster demo (v0.12.x). For a one-command docker compose up

cluster (2 loomcycle replicas, Postgres, nginx LB) with a verify script, see examples/cluster/README.md. Full operator runbook in

.

docs/MULTI-REPLICA.md

v1.0.0: feature-complete, hardened, distribution-ready. 🌳 The 1.0 milestone — the point the roadmap pointed at since the multi-tenant-auth capstone (v0.17.0) and the substrate-completeness line (v0.18–v0.23). 1.0 adds no new primitives; it's the stable tag on the runtime that stabilised across v0.8→v0.23 (the providers, built-in tools, substrate Defs, triggers, multi-tenant authz, HA) and was hardened across v0.24→v0.37 (interactive terminal, /resume/snapshot + cross-instance resume, the context-compaction subsystem, context-transform plugins, external fan-out on every transport, slow-local-model robustness). Distribution is wired end-to-end: Homebrew + multi-arch Docker, init

/ doctor

first-run, the Claude Code plugin, the TS (@loomcycle/client

) + Python adapters, and the embedded Web UI. Apache-2.0. Code-identical to v0.37.0 — 1.0 is the stability stamp, not a feature delta. Beyond 1.0 (unscheduled): a settings UI, an operator cookbook, Helm.

v0.37.0: slow-local-model robustness + aliases-first docs. Two loop fixes from a slow-local-model stress test, plus a config/docs pass. (1) Heartbeat during a model call (#502)OnHeartbeat

fired only at iteration start, so a single iteration that blocked far longer than the cadence (a large-context prefill on a slow local model, or a same-provider retry) let the heartbeat go stale and the stale-run sweeper reaped the live run as heartbeat_timeout

. A run-lifetime ticker now pulses every 30s while the run goroutine is alive; the HTTP timeouts remain the authority on a genuinely stuck call. (2) Compaction caps the kept tail to the window (#503) — auto-compaction could "succeed" yet leave the context still over the window (a tool-heavy agent's keep_last_n

tail of huge file reads); the loop now folds the oldest kept turns into the summary until the tail fits ~half the window, so compaction always relieves pressure. (3) Aliases-first config + local-model guide (#504)loomcycle.example.yaml

restructured aliases-first, a new docs/CONFIGURATION.md

§6b "Local models (Ollama)" (the global num_ctx

knob, header/idle timeouts, compaction tuning), a new loomcycle.local-interactive.example.yaml

, and a runs-page chip fix. Validated by a 133-minute standalone interactive code-reviewer

run on a local GPU; the one edge it surfaced (compaction can't reduce a single indivisible tool-chain) is captured for a follow-up. Runtime + docs; no @loomcycle/client

bump.

v0.36.0: jailed agents can see their sandbox + a roomier run terminal. Two features. (1) Agents jailed to a filesystem sandbox kept addressing files with absolute host paths, which resolve outside the root and fail — because the Read

/Write

/Edit

path params said "Absolute file path" (what the model reads every turn) even though the resolver anchors relative paths to the root. The descriptions now instruct relative paths, and ** Context op=self** additionally reports the jail (

sandbox.read_root

/write_root

/bash_cwd

  • the relative-path convention) and the granted host allowlist (network.allowed_hosts

  • source

), so an agent can introspect its sandbox instead of guessing. docs/TOOLS.md

is corrected too (it documented the old relative-to-process-cwd behaviour). (2) The run page's left column (interactive-sessions switcher + run form) is now collapsible to a thin strip showing the running-interactive count, so the live terminal can use the full width during a run. Runtime + Web UI + docs; op=self fields are additive; no

@loomcycle/client

bump (#499, #500).v0.35.0: model aliases work in tier candidates. A models:

alias (e.g. local-gemma → {ollama-local, gemma4:max}

) now resolves anywhere a tier candidate is accepted — per-agent models:

, user_tiers.*.tiers

, and the library tiers:

— not only in an agent pin. Previously a tier candidate naming an alias failed with 503 no provider available for requested tier

because the resolver matched the model string literally. Expansion now happens at the two resolver-entry boundaries through one shared helper (the same rule the pin path uses), covering HTTP, gRPC, and dynamic / Web-UI / MCP-authored agents. A candidate can also be written as a bare alias string (- local-gemma

), and both config-load validation and the Web UI Library editor understand aliases. Wire-shape-neutral; no @loomcycle/client

bump (#497).

v0.34.5 patch: Ollama reports the model's real loaded context window. Runtime + docs. The ollama

/ ollama-local

context gauge previously showed a window only when LOOMCYCLE_OLLAMA_LOCAL_NUM_CTX

was pinned — and that knob is also sent as options.num_ctx

, so it both caps and reports the context, overriding the ollama server's own setting. With it unset, loomcycle reported "unknown" even when ollama loaded the model at a larger window (a 256K-trained model running at a real 128K). The driver now reads the actual loaded context_length from ollama's /api/ps at the stream's done frame (the model is in VRAM by then) and stamps it on the usage event — so the gauge reflects what ollama actually allocated. An explicit

num_ctx

still wins; a not-yet-loaded model reports 0 ("unknown"); per-model cached, best-effort (gauge-only, never correctness). The loop prefers this per-call window over the static capability default (#495). Docs: the architecture diagram + ARCHITECTURE.md

now show the context-transform plugin layer (#493), plus a README v1.0 voice refresh (#494). No @loomcycle/client

bump.v0.34.4 patch: interactive-terminal UX, local-model fixes, two sandbox/Library fixes. Web UI + runtime; no new primitives.

(1) Interactive-session switcher (#491). Leaving the /run

terminal stranded an interactive run behind the runs-page "resume in terminal" link. The run page (Single tab) now has a collapsible Interactive sessions list in its left column. Each row is one of the operator's running interactive sessions, re-attaching in the terminal on click (replay + live-tail), the current one marked open, collapsed shows "N interactive sessions". The runs page (tree + detail) gains an ** interactive** tag. Backed by an additive

interactive

field on the GET /v1/users/{id}/agents

row.(2) Terminal waiting indicator (#488). A flashing indicator with an adaptive label ("running <tool>

…" vs "waiting for the model…") while the agent works, so a slow turn doesn't look stalled.

(3) Local Ollama (#488). The context gauge renders the operator-pinned num_ctx

as the window (Capabilities().MaxContextTokens

was hard-coded 0

), and ollama-local

gets generous 300s / 300s default timeouts (overridable via LOOMCYCLE_OLLAMA_LOCAL_HEADER_TIMEOUT_MS

/ _IDLE_TIMEOUT_MS

) so a cold local model isn't cut off before its first token.

(4) Sandbox paths (#489). The file tools resolved a relative path against the loomcycle process cwd, disagreeing with the Bash tool (cwd = jail). This let a relative tool path land outside the sandbox (cryptic ENOTDIR

when a like-named file sat at the server's cwd). Relative targets now anchor to the sandbox root. Absolute paths and the symlink-escape guard are unchanged.

(5) Static agent base in the Library (#490). A static agent buried under retired/inactive dynamic versions (no active pointer) is now surfaced as the effective lineage row and is editable/forkable again ("Edit (forks from yaml)"). The runtime already resolved it; this was a UI visibility fix.

No @loomcycle/client

bump.

v0.34.3 patch: Context op=self footprint is fresh after a compaction. A compaction rewrites the loop's in-memory history to

[summary, ack] ++ last-N

. But the context footprint the loop tracks (

lastCtxTokens

) was only ever updated from a completedprovider turn's usage. That's the value

Context op=self

reports as used_tokens

/ used_pct

, and the same value the auto-compact threshold reads. So for one turn after a compaction the agent kept reporting its pre-compaction size (e.g.

~164k / 82%

) even though the actual outbound request had already shrunk (the operator saw in=1504

on the wire).The loop now refreshes lastCtxTokens

(via estimateMessageTokens

, the same estimator behind the context_compaction

event's before/after numbers) at every compaction site: the parked-run steer.KindCompact

path, the running-run drainSteer

KindCompact

path, and the inline auto/self maybeAutoCompact

path. The footprint stamp also moves below the loop's compaction block so a same-turn op=self

is correct too. Fail-before regression test (TestRun_Interactive_ContextUsageRefreshedAfterCompaction

). Runtime-only; no @loomcycle/client

bump.

v0.34.2: Web UI design system + light/dark theming. No runtime primitives. A Web UI design pass and two small fixes.

(1) Tokenized design system. A new --lc-*

token layer (web/src/tokens.css

) mirrors the brand design system: spacing, type-scale, radius, shadow, fonts, semantic colors. The legacy --bg

/ --fg

/ --accent

/ … names become aliases of the themed tokens, so the whole stylesheet themes for free.

(2) Light + dark themes. Default follows the OS prefers-color-scheme

. A persistent topbar sun/moon toggle overrides it (localStorage), with a pre-paint script so there's no flash-of-wrong-theme. Dark is the current palette verbatim; light ships as a functional basic-neutral palette (the brand-cream refinement is the next step).

(3) Brand fonts + accent. Self-hosted, bundled Outfit (display), Inter (body), JetBrains Mono (code). No CDN, embedded, offline-safe. The accent moves from light-blue #5b9dff

to the loom-wood brand green ** #56c596** everywhere (CSS + charts). Form controls and the Activity charts theme against the tokens, and the topbar wordmark swaps per theme (near-white on dark, black-ink on light).

(4) Fixes. Interactive runs are now unbounded by default (an interactive terminal no longer stops after 16 turns with max_iterations

; the runaway guard was never meant for an operator-driven, Cancel-bounded session, and an explicit max_iterations

is still honored). The TestSchedulerBearerCompound

-race

load-flake is fixed at the root (the 310-scale load test is capped under -race

). The agent editor's advanced (raw overlay) now round-trips visibly: it pre-fills from the source on reopen instead of starting empty (the overlay was always persisted; the empty box just made it look unsaved).

Web-UI / CI only; no @loomcycle/client

bump.

v0.34.1: hardening + branding (no new features). A security-hardening and cosmetic release on the road to v1.0.

(1) Central tenant-scoping (security review S2). The per-handler tenant-isolation convention (tenantVisible

/ sessionOwnershipOK

) becomes a single choke-point: a per-request ** tenantScopedStore** accessor that folds a cross-tenant row into an opaque

*store.ErrNotFound

(no existence oracle). Three live cross-tenant read gaps are closed: the run-scoped interrupt list (

GET /v1/runs/{id}/interrupts

), the user interrupt inbox (GET /v1/users/{id}/interrupts

, via a new tenantID

arg on store.InterruptListByUser

), and the user run-state stream (GET /v1/users/{id}/agents/stream

, via a TenantID

on the run-state event + a filter). Per-user channel routes are gated to the principal's own subject. The whole-tenant model is preserved: same-tenant subjects collaborate, super-admin sees all.(2) New brand identity in the Web UI. The topbar shows the new loomcycle wordmark logo (top-left; the dark-theme variant has the wordmark recoloured to the theme foreground, loom-mark colours kept) and the new favicon.

Runtime change is server-side only; no @loomcycle/client

bump.

v0.34.0: context-transform plugins, exp7 (v0.33.0 re-run) hardening, and a cross-provider thinking-fallback fix. One new primitive, one hardening line, one fix line.

(1) Context-transform plugins (RFC Z Phase 1a). A runtime-wide plugin chain sits between the agent's assembled context and the outbound LLM request, transforming a copy. Deterministic, copy-on-write; the caller's history is never mutated. The synthetic code-js

provider is exempt so replay stays byte-stable. Phase 1a ships the ** redact** plugin: outbound secret scrubbing that reuses the F32

redact.Redactor

. Tier-A is exact env-value masking; Tier-B is heuristic patterns (Authorization

, sk-

, AKIA

, xox

, ghp_

, key=value

). The model never sees a configured secret, even when it leaks into history. Configured via a top-level context_plugins:

block.(2) exp7 self-review re-run hardening. Every finding from a 10-agent fan-out review was independently verified against main

(≈9 of ~40 refuted on verification, including a Go-1.24 crypto/rand

-never-errors catch). The confirmed set landed as correctness / robustness fixes: admin POST MaxBytesReader

caps, ExportPretty

checksum, an OAuth-refresher Stop()

-before-Start()

deadlock, a HeartbeatRunner

cancel race, a bounded backplane publish in Bus.Notify

, scheduler on_complete

hooks on the survival ctx, Glob

/Grep

idempotency, an absolute-in-root Glob

pattern (R1), evaluation-dimensions

parse logging, cmd shutdown-budget + SSE-safe IdleTimeout

. Plus a dead-code / cosmetic cleanup sweep.

(3) R2: cross-provider thinking-model fallback downgrade. A DeepSeek thinking model (deepseek-reasoner

/ *-pro

) 400s ("reasoning_content must be passed back") when a fallback hands it a history whose assistant turns lack reasoning_content

(a foreign provider produced them, or the reasoning strip zeroed them). A new optional providers.ThinkingDowngrader

lets the loop downgrade to the non-thinking sibling (reasoner

chat

, *-pro

*-flash

) for that leg, emitting a new model_downgraded

event.

(4) @loomcycle/client 0.34.0. Version-aligned lockstep release; no client-surface change. The new event passes through the generic stream; context plugins are server config.

v0.33.0: external fan-out, the run-mutation surface on every transport, and exp7 hardening. Three feature lines and a self-review fix line.

(1) RFC Y external fan-out. ** POST /v1/runs:batch** and a

MCP tool (mode

spawn_runs

"join"

) spawn up to 32 fresh runs server-side concurrent in one call. Bounded by the existing per-user admission gate. Returns a combined

index-aligned envelope once all settle. A per-child failure rides in-envelope (

status

  • error

), never failing the batch. The batch caller's authoritative tenant stamps every child. Replaces the "fire N serializing spawn_run

calls" / in-loomcycle-dispatcher workaround. (mode: "detach"

awaits RFC P. timeout_ms

caps the join.)(2) Compaction + sampling on every transport. A ** compact_run** MCP tool and a

gRPC RPC (the

CompactRun

POST /v1/runs/{id}/compact

op lifted to a shared connector.CompactRun

; HTTP byte-identical). Per-run and

sampling

overrides now on

compaction

spawn_run

/ spawn_runs

(MCP), the gRPC RunRequest

/ ContinueRequest

(proto3 optional

, so temperature: 0

stays deterministic), and @loomcycle/client

's runStreaming

/ continueSession

.(3) @loomcycle/client 0.33.0. New

spawnRunBatch()

  • compactRun()

  • per-run sampling / compaction (52 → 54 methods).(4) exp7 self-review. Tenant-scope DynamicAgentDelete

(cross-tenant delete), infra-secret YAML-expand deny + newline reject, /v1/runs/{id}/input

scope-gate, scheduler error logging, an O(1) ChannelGet

, an additive snapshot checksum, and three smaller hardening fixes.

v0.32.0: context compaction subsystem (keep-last-N, auto-compact, per-agent settings + spawn inheritance). A long session crowds the model's window. Compaction summarizes older turns and continues from the summary. The loop's in-memory history is replaced with [pinned task? + summary, ack] ++ last-N kept verbatim

, snapped to a clean user-turn boundary so a tool_use

/ tool_result

pair is never split. A context_compaction

marker records summary + keep-N / keep-first so replayTranscript

rebuilds the identical form on resume (full transcript retained, non-destructive).

Four triggers, one shared summarizer (loop.Summarize

):

manual. The/run

Compact button callsPOST /v1/runs/{id}/compact

.auto. Whencompaction.enabled

and the footprint crossesautocompact_at_pct

, the loop compacts inline at a boundary. Works forautonomous runs too. Off by default, self-debouncing.self.Context op=compact

.

All three emit the marker and an OTEL context.compaction

span event.

The per-agent ** compaction** block mirrors

sampling

: yaml, AgentDef overlay, per-run, content-identifying, exposed by Context op=self

. Fields: enabled

, target_percentage

(10-50), keep_last_n

, keep_first

, autocompact_at_pct

(50-95), optional cheaper summary model

. The block flows down the spawn tree: a child inherits the parent's effective policy, its own def fills the gaps, and the parent overrides per-spawn via the Agent tool. Bundles the

/run

composer restyle (#458), the ✕ Stop button (#459), and the manual Compact button (#460). Runtime-only; no @loomcycle/client

bump.v0.31.0: park + resume a fan-out parent blocked in parallel_spawn (F42 / RFC X Phase 3). Closes the documented Phase-2 deferral. A run blocked inside

Agent.parallel_spawn

wg.Wait()

is inside a tool call, not at the loop's only park point, so on it never parked.

d_runs_count

excluded it, the Manager warned "fan-out PARENT … did not reach a boundary", and a mid-fan-out snapshot missed the parent. v0.31.0 fixes both sides, gated behind(default OFF, so existing behavior is byte-identical until opt-in).

LOOMCYCLE_RESUME_FANOUT

(1) Capture. A -watcher goroutine in executeParallelSpawn

calls the existing Gate.Park

on and unparks on resume, without touching wg.Wait or result collection. The parent now counts as parked (warning gone, count accurate) and a same-instance → resume mid-fan-out just works.

(2) Durability. A two-event spawn ledger on the parent transcript: spawn_child_started

is index → run_id, spawn_child_result

is a child that finished pre-snapshot. Rides the existing event emitter, no schema change, ignored by replayTranscript

.

(3) Resume. resumedRun

detects the parked fan-out parent. In its background goroutine, before taking a run slot (no semaphore deadlock), it reconciles each child (durable ledger result, else awaits the re-dispatched child to terminal and reads its transcript), synthesizes the byte-compatible {"results": [...]}

envelope, and seeds it into PriorMessages

so the loop continues. Edges: pre-snapshot completion, gone agent (error result), never-dispatched-past-cap (re-issuable error), depth > 1.

Deferred: a mixed tool turn (parked fan-out + sibling in-flight tools) is flagged for manual re-attach. Default-ON awaits exp6.5 re-validation. Runtime-only; no @loomcycle/client

bump.

v0.30.0: cross-instance resume of a snapshotted mid-run (F42 / RFC X Phase 2). v0.28.0 made ``

quiesce in-flight runs (Phase 1) so a mid-run snapshot is reliable. But a snapshotted _state='d'

run restored on another instance was data only: nothing relaunched its loop. POST /v1/_resume

returned 409 not_d

, and a restart didn't relaunch it.

v0.30.0 re-dispatches d runs by reconstructing their loop from the transcript. ResumedRuns

re-resolves the agent, replays the transcript into PriorMessages

, flips the row to running

, re-registers cancel / / steer, and re-enters loop.Run

under the existing run_id in a background goroutine. It fires after a snapshot restore (response reports d_runs_resumed

) and at boot for crash recovery (cluster-gated by an advisory lock so one replica resurrects each run).

A new additive runs.interactive

column (captured + restored) preserves park-vs-complete semantics. The stale-run sweeper now skips parked (d

/ pausing

) runs so they aren't killed before resume.

Limitations: per-run secrets (user_bearer

/ credentials) and call-time overrides (allowed_hosts / sampling / metadata) aren't snapshotted; they're re-derived from the agent def. A run idle-awaiting-input when d is flagged for manual re-attach, not auto-resumed. Runtime-only; no @loomcycle/client

bump.

v0.29.1 patch: adapter lockstep publish. The additive max_context_tokens

usage-event field (v0.29.0) shipped in the runtime but the @loomcycle/client

npm publish skipped. The publish workflow only fires when the adapter's package.json

version equals the release tag, and it was at 0.26.0

. v0.29.1 realigns the adapter version with the tag so @loomcycle/client@0.29.1

publishes with the field. No runtime change (binaries identical to v0.29.0).

v0.29.0: Web UI + operability (agent-editor controls, terminal UX, soft reclaim). Three operator-facing improvements (no new runtime primitives).

(1) Agent editor (#449). Dedicated sampling controls (temperature / top_p / top_k / penalties / seed / stop, string-typed so blank means unset and 0

means explicit). Plus a collapsible advanced JSON / YAML overlay for the long tail (channels, interruption, *_def_scopes

, …) the substrate already accepts. Empty box never blocks; a malformed non-empty body blocks inline.

(2) Interactive terminal (#450). Your own messages now echo into the transcript (❯ …

for initial prompt, steer, continue; they were filtered from the live tail). Plus a context-size gauge ctx 47.2k / 200k (24%)

backed by an additive max_context_tokens

on the usage event. @loomcycle/client

publishes the field in 0.29.1 (the v0.29.0 adapter publish skipped on a version mismatch); gRPC parity is a fast-follow.

(3) Soft reclaim (#452). Retiring the active agent now clears the active pointer so the name is reclaimable. Recreate to grant more tools: a fork can't widen the allowed_tools

ceiling, a fresh create can. Also fixes a latent bug where a retired-but-active def was still served to runs. The Library badges inactive / retired names. No hard delete; full audit lineage preserved.

Plus a bundled examples/exp6-self-evolving-agents/

(#451). allowed_hosts

per-run narrowing already lives in the run launcher (caller-authoritative).

v0.28.0: per-agent LLM sampling, and actually quiesces. Two features.

(1) Per-agent sampling. A grouped sampling:

block (temperature

, top_p

, top_k

, frequency_penalty

, presence_penalty

, seed

, stop

), settable via static yaml, the AgentDef substrate (create / fork; this is how a self-evolving breeder mints variants), and per-instance on POST /v1/runs

. Overlays / overrides merge per field: per-run > per-agent > provider default. (temperature: 0.0

is deterministic, not unset.) Each driver maps what its provider supports; Anthropic drops temperature when effort

engages thinking. Content-identifying. Reported back via Context op=self

.

(2) cooperative quiesce (F41 / RFC X). The run loop now parks at a clean iteration boundary.

()

waits (up to timeout_ms

) for in-flight runs to park, so d_runs_count

is accurate. New runs are 503-gated on /v1/runs

, gRPC, and webhook / A2A. That makes " + snapshot a mid-run" reliable. (A fan-out parent mid-parallel_spawn

is the documented Phase-2 deferral.) Runtime-only; no @loomcycle/client

bump.v0.27.2 patch: collapsed tool results actually fold. The collapsed tool_result

summary used oneLine(text)

(flattens whitespace, doesn't truncate), so a large result showed in full whether folded or not. It's now truncated to a 100-char summary like tool_call

. The full output stays in the expand. Frontend-only.

v0.27.1 patch: interactive-terminal Web UI polish. Three follow-ups to the v0.27.0 terminal. The transcript now auto-scrolls to follow live output. (Streaming text coalesces into one line, so the old line-count trigger stalled the tail; it now follows the events

stream with a stick-to-bottom ref that s when you scroll up.) ** tool_call collapses** to a one-line summary + expand-on-click, so a

Write

's full file body no longer floods the scrollback, matching tool_result

. And the continue / steer box is a multi-line: Enter sends, Shift+Enter inserts a newline, auto-growing up to a cap. Frontend-only; no

<textarea>

@loomcycle/client

bump.v0.27.0: interactive runs survive leaving the terminal, and you can come back. v0.26.x's interactive /run

run was bound to its HTTP request. Navigating to the runs menu closed the SSE stream, cancelled the request ctx, and killed the parked run.

v0.27.0 runs an interactive run in a background goroutine under context.WithoutCancel

. That keeps the request's auth / tenant values; the run isn't cancelled on disconnect and stops only via the cancel registry. It also adds ** GET /v1/runs/{run_id}/stream** to

re-attach: replay from

?from_seq

  • live-tail, re-emitting stored events as SSE frames. ScopeRunsRead

  • tenant-ownership gated. A new run-scoped incremental store read (GetRunEventsSince

, sqlite + postgres) backs the tail. A "resume in terminal" link on a running agent in the runs list is the way back.

Two more changes ride along. ** Context op=self** now returns the resolved

and

provider

(non-secret introspection, stamped per-iteration so it's fallback-truthful). The terminal UI caps its height (inner-scroll instead of growing the page) and

model

collapses tool results(one-line summary + expand-on-click; operator / agent messages stay full).

Behaviour note: the steer echo frame is no longer on the live wire for interactive runs (steering itself is unchanged). Single-replica re-attach (DB-backed deployments work cluster-wide since events are in the shared store). Cross-replica + multi-viewer deferred. Adds one GET route; no @loomcycle/client

bump.

v0.4 → v0.26.x foundation and substrate build-out. Summarized in the changelog table above. Full per-version detail in REVISIONS.md.

Planned: v1.0 (hardening + distribution).

No new features are planned before v1.0. The feature set is complete. The remaining work is the in-progress test / QA + security-hardening pass across the shipped surfaces. Once that's green, the v1.0 tag ships. No new primitives, no new wire surface. Every change from here is a fix, a test, or distribution polish. (With the multi-tenant-auth capstone shipped in v0.17.0, v1.0 is a pure hardening + distribution milestone.)

8-hour stability soak completed: 1.27M circuits, 3.8M agent runs, 100% completion across 468 waves, zero leaks.

Distribution + bootstrapping. A first-run install story that survives contact with a fresh machine. HardenedHomebrew formula andDocker images (multi-arch, theinit

/doctor

flow, a sane default config), sobrew install

/docker run

gets an operator to a working sidecar without reading the docs first.Claude Code plugin hardening. Theclaude-code-plugin-loomcycle

plugin (slash commands + skills + hooks overloomcycle mcp

) gets a hardening pass: error surfaces, version-skew handling, and a clean bootstrap from the published binary.Security + runtime-QA pass across the v0.13-v0.17 surfaces (A2A, webhooks, pluggable memory + the memory layer, the code-js provider, the multi-tenant-auth substrate). Then thev1.0 tag.Enterprise auth(SSO / RBAC / SCIM / signed, queryable audit) stays out of scope for OSS. It's a separate edition built on the sameOperatorTokenDef

substrate.Beyond(polish): a settings UI, an operator cookbook of postures, broader distribution (Helm).

Post-v1.0 design RFCs.

Three named design lines beyond v1.0. Designs are drafted; locks and PRs come after the v1.0 hardening pass clears.

Context-compress plugin (RFC Z Phase 2). A second built-in plugin in the same contextplugin chain that shipsredact

in v0.34.0. Operator-configurable, LLMLingua-style content compression at the per-turn boundary: tokenizer + content compressor compose withredact

, transform a copy of the outbound request, leave the canonical history and the persisted transcript untouched. The seam is the same one auto-compaction already uses; the new dependency is a tokenizer.**In preparation.**SQL Memory (RFC AA). A second facet of the Memory primitive: per-scope SQL databases the runtime owns, isolated from the main loomcycle store, that sandboxed agents query with arbitrary SQL. Two new Memory ops (sql_query

,sql_exec

), durable per-(tenant, scope, scope_id)

plus an ephemeral per-run scratch DB, default-denysql_scopes

ACL, statement timeouts, byte quotas, full audit. sqlite tier first (one file per scope, hardened authorizer + statement allowlist); postgres tier (one schema per scope in a separate aux DB) is Phase 2. The "agents that need structured tables today needBash + sqlite3

" gap.Capability-based memory interface + mem0 backend (RFC K). Generalize the v0.15.0memory.Backend

contract with an optionalMemoryLayer

capability so LLM-extract memory products work natively (add(messages) → recall(query)

) rather than degraded into a KV store. mem0 lands as the firstMemoryLayer

backend (Apache-2.0, 57k★, daily commits). The flatBackend

stays canonical; an external memory-layer backend declinesBackend

and servesMemoryLayer

only. Mem9 demotes to PREVIEW and re-targets atMemoryLayer

.

Full per-version release notes: REVISIONS.md. Public roadmap with v0.8.x → v1.0 design details:

.

docs/PLAN.md

Three diagrams cover different views of the same runtime:

Diagram source: docs/architecture.d2 (regenerate with

d2 docs/architecture.d2 docs/assets/architecture.png

).Connector detail. The v0.8.15 Connector

abstraction layer (the pink block in the middle of the main diagram) is the architectural anchor every wire transport dispatches through. The detail diagram enumerates all 36 methods and shows which transports IMPLEMENT, CONSUME, and MIRROR the interface:

Source: docs/architecture-connector.d2.

Multi-replica cluster mode (v0.12.x). When LOOMCYCLE_REPLICA_ID

is set per process and the Postgres backend is used, loomcycle runs as a cluster behind any HTTP load balancer. The shared Postgres doubles as the LISTEN / NOTIFY backplane for cross-replica cancel, / resume, run-state fanout, and quota notifications. SQLite refuses cluster mode at boot.

Source: docs/architecture-cluster.d2. Operator runbook:

. Demo:

docs/MULTI-REPLICA.md

.

examples/cluster/README.md

Full request flow, abstractions, and concurrency model: docs/ARCHITECTURE.md.

TypeScript.npm install @loomcycle/client

(see). HTTP + SSE.adapters/ts/

Python.pip install loomcycle

(see). Async overadapters/python/

grpc.aio

.

No vendor binary in the loop. Pure HTTP to provider APIs. No subprocess auth inheritance.Default-deny everything. Every built-in tool is disabled until env-configured. Every agent gets zero tools untilallowed_tools

is set.Two-layer policy + per-request narrowing. Operator floor in env; agent narrowing in yaml; caller narrowing per-run. Caller can never widen.SSRF defence. Hostname allowlist + RFC1918/loopback/link-local IP block at the dial layer. Defeats DNS rebinding.Constant-time bearer auth.sha256+CTC

on both HTTP and gRPC.Run inside a container or VM if you need real isolation.Bash

is restricted, not isolated.

Full security model and the two-layer default-deny walkthrough: docs/TOOLS.md.

Repo-side docs (this directory):

. Request flow, provider abstraction, agent loop, sub-agents, skills, storage, concurrency, cancellation.docs/ARCHITECTURE.md

. Two-layer default-deny model, every built-in tool, MCP / LocalAPI integrations, per-request narrowing.docs/TOOLS.md

. End-to-end MCP HTTP pipeline: request lifecycle,docs/MCP_INTEGRATION.md

${run.user_bearer}

substitution, model-visibility boundary, recipe for wrapping a REST API as an MCP server consumable by loomcycle.. Register loomcycle as an MCP server in Claude Code / Claude Desktop. Copy-paste config snippets for Docker / Homebrew / direct-binary transports, plus thedocs/MCP_SERVER.md

loomcycle mcp install

helper.. Driving loomcycle from Claude Code: the recommendeddocs/CLAUDE-CODE.md

claude-code-plugin-loomcycle

plugin (slash commands + skills + hooks) vs. the manualloomcycle mcp install

path.. Operator config guide: provider / tier / user_tier resolution rules, four cookbook patterns (single / multi-provider × single / multi-user-tier),docs/CONFIGURATION.md

models:

alias map, and the agent.md

frontmatter field reference.. Postgres backend operator guide: configuration, migrations, sqlite → postgres runbook, concurrency benchmark.docs/POSTGRES.md

. gRPC surface: enablement, wire-shape parity with HTTP + SSE, error mapping, Python adapter quick-start.docs/GRPC.md

. Public roadmap: shipped v0.4 → v0.8.12; planned v0.8.13 → v1.0.docs/PLAN.md

. Per-version release notes (v0.4.0 onward).REVISIONS.md

. Contribution policy (closed for external PRs until v1.x).CONTRIBUTING.md

. Project guide for agents working in this repo (Claude Code).CLAUDE.md

In-binary docs (bundled Context.help

topics; agents read these directly, operators hit GET /v1/_help/<topic>

against a running instance):

installation

. All four install paths (Homebrew, Docker,go install

, direct tarball) with verification + troubleshooting.getting-started

. First-run walkthrough:init

→ set env vars →doctor

→ run.llm-gateway

. Direct LLM routing endpoint (v0.11.0; for n8n + LangChain consumers).openai-compat

. Drop-in OpenAI SDK shims (v0.11.3 chat + v0.11.4 embeddings) with Python + TypeScript examples.fairness

. Per-user concurrency quota policy.observability

. OTEL trace export setup.vector-memory

,voyage-embedder

,sqlite-vec

. Vector Memory backends.dynamic-mcp

. Register MCP servers at runtime.bash-security

. The Bash tool's restricted-not-isolated security posture.

Full list via GET /v1/_help

against a running instance.

If loomcycle is useful to you or your team, GitHub Sponsors helps fund continued development. Individual supporters and corporate sponsors both welcome.

The runtime stays Apache-2.0 either way. Sponsorships fund the v1.x runway: Helm chart, operator cookbook, settings UI, and the sustained engineering that keeps the binary small and the substrate stable.

Current sponsors are listed in BACKERS.md (and at

loomcycle.dev/sponsorswith logos).

Apache-2.0. See LICENSE.

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