fix: docs/CLAUDE-AUTH-CONCURRENCY.md: rewrite for shared CLAUDE_CONFIG_DIR approach (#646)
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Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This commit is contained in:
Claude 2026-04-10 21:16:18 +00:00
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# Claude Code OAuth Concurrency Model # Claude Code OAuth Concurrency Model
## TL;DR ## Problem statement
The factory runs N+1 concurrent Claude Code processes across containers The factory runs multiple concurrent Claude Code processes across
that all share `~/.claude` via bind mount. To avoid OAuth refresh races, containers. OAuth access tokens are short-lived; refresh tokens rotate
they MUST be serialized by the external `flock` on on each use. If two processes POST the same refresh token to Anthropic's
`${HOME}/.claude/session.lock` in `lib/agent-sdk.sh`. Claude Code's token endpoint simultaneously, only one wins — the other gets
internal OAuth refresh lock does **not** work across containers in our `invalid_grant` and the operator is forced to re-login.
mount layout. Do not remove the external flock without also fixing the
lockfile placement upstream.
## What we run Claude Code already serializes OAuth refreshes internally using
`proper-lockfile` (`src/utils/auth.ts:1485-1491`):
| Container | Claude Code processes | Mount of `~/.claude` | ```typescript
|---|---|---| release = await lockfile.lock(claudeDir)
| `disinto-agents` (persistent) | polling-loop agents via `lib/agent-sdk.sh::agent_run` | `/home/johba/.claude``/home/agent/.claude` (rw) | ```
| `disinto-edge` (persistent) | none directly — spawns transient containers via `docker/edge/dispatcher.sh` | n/a |
| transient containers spawned by `dispatcher.sh` | one-shot `claude` per invocation | same mount, same path |
All N+1 processes can hit the OAuth refresh window concurrently when `proper-lockfile` creates a lockfile via an atomic `mkdir(${path}.lock)`
the access token nears expiry. call — a cross-process primitive that works across any number of
processes on the same filesystem. The problem was never the lock
implementation; it was that our old per-container bind-mount layout
(`~/.claude` mounted but `/home/agent/` container-local) caused each
container to compute a different lockfile path, so the locks never
coordinated.
## The race ## The fix: shared `CLAUDE_CONFIG_DIR`
OAuth access tokens are short-lived; refresh tokens rotate on each `CLAUDE_CONFIG_DIR` is an officially supported env var in Claude Code
refresh. If two processes both POST the same refresh token to (`src/utils/envUtils.ts`). It controls where Claude resolves its config
Anthropic's token endpoint simultaneously, only one wins — the other directory instead of the default `~/.claude`.
gets `invalid_grant` and the operator is forced to re-login.
Historically this manifested as "agents losing auth, frequent re-logins", By setting `CLAUDE_CONFIG_DIR` to a path on a shared bind mount, every
which is the original reason `lib/agent-sdk.sh` introduced the external container computes the **same** lockfile location. `proper-lockfile`'s
flock. The current shape (post-#606 watchdog work) is at atomic `mkdir(${CLAUDE_CONFIG_DIR}.lock)` then gives free cross-container
`lib/agent-sdk.sh:139,144`: serialization — no external wrapper needed.
## Current layout
```
Host filesystem:
/var/lib/disinto/claude-shared/ ← CLAUDE_SHARED_DIR
└── config/ ← CLAUDE_CONFIG_DIR
├── credentials.json
├── settings.json
└── ...
Inside every container:
Same absolute path: /var/lib/disinto/claude-shared/config
Env: CLAUDE_CONFIG_DIR=/var/lib/disinto/claude-shared/config
```
The shared directory is mounted at the **same absolute path** inside
every container, so `proper-lockfile` resolves an identical lock path
everywhere.
### Where these values are defined
| What | Where |
|------|-------|
| Defaults for `CLAUDE_SHARED_DIR`, `CLAUDE_CONFIG_DIR` | `lib/env.sh:138-140` |
| `.env` documentation | `.env.example:92-99` |
| Container mounts + env passthrough (edge dispatcher) | `docker/edge/dispatcher.sh:446-448` (and analogous blocks for reproduce, triage, verify) |
| Auth detection using `CLAUDE_CONFIG_DIR` | `docker/agents/entrypoint.sh:101-102` |
| Bootstrap / migration during `disinto init` | `lib/claude-config.sh:setup_claude_config_dir()`, `bin/disinto:952-962` |
## Migration for existing dev boxes
For operators upgrading from the old `~/.claude` bind-mount layout,
`disinto init` handles the migration interactively (or with `--yes`).
The manual equivalent is:
```bash
# 1. Stop the factory
disinto down
# 2. Create the shared directory
mkdir -p /var/lib/disinto/claude-shared
# 3. Move existing config
mv "$HOME/.claude" /var/lib/disinto/claude-shared/config
# 4. Create a back-compat symlink so host-side claude still works
ln -sfn /var/lib/disinto/claude-shared/config "$HOME/.claude"
# 5. Export the env var (add to shell rc for persistence)
export CLAUDE_CONFIG_DIR=/var/lib/disinto/claude-shared/config
# 6. Start the factory
disinto up
```
## Verification
Watch for these analytics events during concurrent agent runs:
| Event | Meaning |
|-------|---------|
| `tengu_oauth_token_refresh_lock_acquiring` | A process is attempting to acquire the refresh lock |
| `tengu_oauth_token_refresh_lock_acquired` | Lock acquired; refresh proceeding |
| `tengu_oauth_token_refresh_lock_retry` | Lock is held by another process; retrying |
| `tengu_oauth_token_refresh_lock_race_resolved` | Contention detected and resolved normally |
| `tengu_oauth_token_refresh_lock_retry_limit_reached` | Lock acquisition failed after all retries |
**Healthy:** `_race_resolved` appearing during contention windows — this
means multiple processes tried to refresh simultaneously and the lock
correctly serialized them.
**Bad:** `_lock_retry_limit_reached` — indicates the lock is stuck or
the shared mount is not working. Verify that `CLAUDE_CONFIG_DIR` resolves
to the same path in all containers and that the filesystem supports
`mkdir` atomicity (any POSIX filesystem does).
## The deferred external `flock` wrapper
`lib/agent-sdk.sh:139,144` still wraps every `claude` invocation in an
external `flock` on `${HOME}/.claude/session.lock`:
```bash ```bash
local lock_file="${HOME}/.claude/session.lock" local lock_file="${HOME}/.claude/session.lock"
@ -40,96 +122,17 @@ output=$(cd "$run_dir" && ( flock -w 600 9 || exit 1;
claude_run_with_watchdog claude "${args[@]}" ) 9>"$lock_file" ...) claude_run_with_watchdog claude "${args[@]}" ) 9>"$lock_file" ...)
``` ```
This serializes every `claude` invocation across every process that With the `CLAUDE_CONFIG_DIR` fix in place, this external lock is
shares `${HOME}/.claude/`. **redundant but harmless** — `proper-lockfile` serializes the refresh
internally, and `flock` serializes the entire invocation externally.
## Why Claude Code's internal lock does not save us The external flock remains as a defense-in-depth measure; removal is
tracked as a separate vision-tier issue.
`src/utils/auth.ts:1491` (read from a leaked TS source — current as of
April 2026) calls:
```typescript
release = await lockfile.lock(claudeDir)
```
with no `lockfilePath` option. `proper-lockfile` defaults to creating
the lock at `<target>.lock` as a **sibling**, so for
`claudeDir = /home/agent/.claude`, the lockfile is created at
`/home/agent/.claude.lock`.
`/home/agent/.claude` is bind-mounted from the host, but `/home/agent/`
itself is part of each container's local overlay filesystem. So each
container creates its own private `/home/agent/.claude.lock` — they
never see each other's locks. The internal cross-process lock is a
no-op across our containers.
Verified empirically:
```
$ docker exec disinto-agents findmnt /home/agent/.claude
TARGET SOURCE FSTYPE
/home/agent/.claude /dev/loop15[/...rootfs/home/johba/.claude] btrfs
$ docker exec disinto-agents findmnt /home/agent
(blank — not a mount, container-local overlay)
$ docker exec disinto-agents touch /home/agent/test-marker
$ docker exec disinto-edge ls /home/agent/test-marker
ls: cannot access '/home/agent/test-marker': No such file or directory
```
(Compare with `src/services/mcp/auth.ts:2097`, which does it correctly
by passing `lockfilePath: join(claudeDir, "mcp-refresh-X.lock")` — that
lockfile lives inside the bind-mounted directory and IS shared. The
OAuth refresh path is an upstream oversight worth filing once we have
bandwidth.)
## How the external flock fixes it
The lock file path `${HOME}/.claude/session.lock` is **inside**
`~/.claude/`, which IS shared via the bind mount. All containers see
the same inode and serialize correctly via `flock`. This is a
sledgehammer (it serializes the entire `claude -p` call, not just the
refresh window) but it works.
## Decision matrix for new claude-using containers
When adding a new container that runs Claude Code:
1. **If the container is a batch / agent context** (long-running calls,
tolerant of serialization): mount the same `~/.claude` and route
all `claude` calls through `lib/agent-sdk.sh::agent_run` so they
take the external flock.
2. **If the container is interactive** (chat, REPL, anything where the
operator is waiting on a response): do NOT join the external flock.
Interactive starvation under the agent loop would be unusable —
chat messages would block waiting for the current agent's
`claude -p` call to finish, which can be minutes, and the 10-min
`flock -w 600` would frequently expire under a busy loop. Instead,
pick one of:
- **Separate OAuth identity**: new `~/.claude-chat/` on the host with
its own `claude auth login`, mounted to the new container's
`/home/agent/.claude`. Independent refresh state.
- **`ANTHROPIC_API_KEY` fallback**: the codebase already supports it
in `docker/agents/entrypoint.sh:119-125`. Different billing track
but trivial config and zero coupling to the agents' OAuth.
3. **Never** mount the parent directory `/home/agent/` instead of just
`.claude/` to "fix" the lockfile placement — exposes too much host
state to the container.
## Future fix
The right long-term fix is upstream: file an issue against Anthropic's
claude-code repo asking that `src/utils/auth.ts:1491` be changed to
follow the pattern at `src/services/mcp/auth.ts:2097` and pass an
explicit `lockfilePath` inside `claudeDir`. Once that lands and we
upgrade, the external flock can become a fast-path no-op or be removed
entirely.
## See also ## See also
- `lib/agent-sdk.sh:139,144` — the external flock - `lib/env.sh:138-140``CLAUDE_SHARED_DIR` / `CLAUDE_CONFIG_DIR` defaults
- `docker/agents/entrypoint.sh:119-125` — the `ANTHROPIC_API_KEY` fallback - `lib/claude-config.sh` — migration helper used by `disinto init`
- Issue #623 — chat container, auth strategy (informed by this doc) - `lib/agent-sdk.sh:139,144` — the external `flock` wrapper (deferred removal)
- `docker/agents/entrypoint.sh:101-102``CLAUDE_CONFIG_DIR` auth detection
- `.env.example:92-99` — operator-facing documentation of the env vars
- Issue #623 — chat container auth strategy