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* fix(tenki): honour start_line and end_line in read_file The base Sandbox contract declares read_file(path, start_line, end_line), and the tools layer passes both keyword arguments on every ranged read — including the continuation path that a truncated read names with its start_line marker. TenkiSandbox.read_file accepted only path, so any ranged read through a Tenki sandbox raised TypeError and surfaced as "Unexpected error reading file"; a truncated read could not be continued. Slice the text the way the other providers do (e2b, opensandbox, boxlite): the full text when no range is given, otherwise the selected lines joined with newlines. * fix(tenki): clamp a negative start_line and pin the out-of-range read contract Mirror LocalSandbox.read_file and clamp the start line to at least 1 so a negative start_line cannot wrap around through Python's negative-index slicing. Also extend the ranged-read test with the two boundary cases the tools layer depends on: a start past EOF returns an empty string, and a negative start reads from the first line. * fix(tenki): clamp a negative end_line in read_file Mirror LocalSandbox.read_file for the symmetric range boundary: clamp a negative end_line to zero so Python's negative-index slicing cannot silently drop the last line. Pin the empty result in the existing ranged-read test.
Tenki backend
Runs each DeerFlow sandbox as a Tenki cloud sandbox — an isolated microVM created from a stock base image, with no daemon or local virtualization to manage. A cloud-hosted alternative to the container-based AIO sandbox and the local-virtualization BoxLite backend.
Configuration
sandbox:
use: deerflow.community.tenki:TenkiSandboxProvider
api_key: $TENKI_API_KEY # falls back to TENKI_API_KEY / TENKI_AUTH_TOKEN env var
base_url: https://tenki.cloud # optional; SDK default when omitted
image: my-base-image # optional; Tenki account default base image when omitted
workspace_id: ws_... # optional; auto-selected if the account has exactly one
cpu_cores: 2 # optional per-sandbox vCPUs
memory_mb: 2048 # optional per-sandbox memory
replicas: 3 # active + warm microVM cap per gateway process (default: 3)
idle_timeout: 600 # warm microVM idle seconds before terminate; 0 disables
max_duration: 14400 # Tenki sandbox lifetime in seconds (default: 4h); 0 uses the account default
sticky: false # pin the microVM to its host (only matters with pause/resume)
home_dir: /home/tenki # writable dir backing /mnt/user-data (default: /home/tenki)
environment: # injected into every command (and as create-time env)
PYTHONUNBUFFERED: "1"
Install the optional SDK before selecting this provider:
pip install "deerflow-harness[tenki]"
The tenki package (which provides the tenki_sandbox module) is an optional
DeerFlow harness extra, not part of the default install. Get an API key from
https://tenki.cloud/docs/sandbox/sdk.
Design
Tenki's Python SDK is synchronous, so — unlike BoxLite — the adapter calls the
SDK directly with no event-loop bridge. Sandboxes are named deterministically
from user_id:thread_id, released into an in-process warm pool after each agent
turn, and reclaimed (after a liveness health check) by the same thread on the
next acquire. A terminal session error evicts the sandbox and the next acquire
rebuilds it; other transport errors surface to the caller (exec is never
auto-retried — it is not idempotent, so re-running could double a command's side
effects). Sandboxes are created with wait=False and awaited via wait_ready()
so a readiness failure still leaves this provider holding the handle to
terminate, and with an explicit max_duration so a long-lived thread does not
lose its sandbox to Tenki's default lifetime mid-conversation.
| File | Role |
|---|---|
provider.py |
SandboxProvider lifecycle, warm pool, scope resolution |
sandbox.py |
Sandbox adapter; execute_command + file ops |
Contract coverage
The full Sandbox surface is implemented. File transport uses Tenki's native sandbox.fs
API; directory and content search shell out and reuse deerflow.sandbox.search,
mirroring e2b_sandbox:
execute_command—sh -lc, with per-call env and timeout.read_file/write_file/update_file— nativefs.read_text/fs.mkdir/fs.write_stream(binary-safe, streamed).download_file— nativefs.read_stream, restricted to the/mnt/user-dataprefix; the 100 MB cap is enforced on bytes actually received, so a file growing mid-transfer cannot slip past it.list_dir/glob/grep—find/grepwith busybox-portable flags (the fs API is single-level and has no content search); results filtered/capped in Python and reported back under/mnt/user-data.
Tenki sandboxes run as the unprivileged tenki user with /mnt root-owned, so
DeerFlow's /mnt/user-data virtual prefix is remapped under the writable
home_dir (like e2b_sandbox). The provider also best-effort sudo-symlinks
/mnt/user-data → home_dir at create time so agent shell commands using the
literal /mnt/... path still work; if sudo is unavailable the file APIs keep
working via the remap.
Warm-pool capacity is governed by sandbox.replicas across active + warm
sandboxes. sandbox.idle_timeout controls how long released warm sandboxes stay
running; 0 disables idle reaping. Active sandboxes are never evicted to satisfy
the cap.
Scope: stable features only
Only the stable Tenki surface is used — sandbox create/terminate plus exec/shell/filesystem over shell commands. Volumes, snapshots, and template builds are intentionally not used, so no prebaked image or unstable Tenki feature is required and any stock base image works.
Not yet implemented (follow-ups): cross-process orphan reconciliation (adopting sandboxes left by a previous gateway process) and a preview-URL surface.
Status
Verified end-to-end against live Tenki sandboxes: provider resolution →
execute_command → full file-op surface (read/write/update/download,
list_dir/glob/grep) → warm-pool reclaim → terminate, plus the
/mnt/user-data sudo symlink. Unit tests run in CI without tenki
installed; test_integration_real_sandbox exercises a real microVM when
TENKI_API_KEY is set.