boxmaker/docs/decisions.md

Decisions

Newest first. A decision that changes docs/design.md lands in the same commit as the change.

Decided

Date	Decision	Reason
2026-09-18	M3 is split. M3a is the decision path: grants and matching, session taint, the hash-chained audit log, approvals through bxctl, the broker.sock and admin.sock protocol, and loopd's BrokerPort; tools do not run (the runner is a trait with a refusing implementation). M3b is the Podman runner, the four tools and the egress proxy. Review happens after each.	The security logic is reviewed before real tools run on it, as with M2a and M2b. Spec docs/specs/2026-09-18-m3a-decision-path.md.
2026-09-18	Grant loading fails closed: one invalid grant file denies every call (grants_invalid) until it is fixed. M3 grants may not set secret or patterns; each tool has fixed rules for which constraints it takes. Among matching grants the most restrictive mode wins (deny, ask, auto). An approval re-decides against the current grants and taint, and runs only if the outcome is still ask or auto.	A skipped, mistyped deny grant would silently become an allow. Pattern-matching shell commands is a false comfort; the container is the boundary.
2026-09-18	Every fail-closed state has an entry in docs/runbook.md with what you see, why, how to confirm, how to fix and how to check; its message ends with see docs/runbook.md#<entry>, and a gate script checks that every referenced entry exists.	Owner's requirement: a refusing system must come with clear, actionable remediation.
2026-09-18	brokerd listens on two sockets: broker.sock (tool requests only, for loopd) and admin.sock (approvals and grant checks, for bxctl). Each refuses the other's messages with forbidden. Replaces the single broker.sock of the pre-M1 spec.	Anything that could reach the approving socket could approve its own calls. Until M7 all roles run as the owner's user, so the split is enforced in code; M7 enforces it with mounts.
2026-09-18	The audit log records events (decision, approval, result, recovery, accepted_break) in one chain. A decision is on disk before anything runs; results are recorded by hash and size, not content. A broken chain stops brokerd until the owner runs it once with --accept-break, which records the break; nothing is ever repaired or deleted. Chain verification is a pure function in proto shared by brokerd and bxctl audit verify. Approval ids are the seq of the decision record.	A secret read must not be copied into the audit log. Verification must work when brokerd refuses to start.
2026-09-18	Secrets move to M4. In M3 a grant that sets secret is invalid.	None of M3's tools needs a secret; the first is the Mattermost bot token.
2026-09-18	Until M7, brokerd and its containers run as the owner's user through rootless Podman; a container escape is the owner's user. Containers are hardened (--network=none unless granted, --read-only, --cap-drop=all, no-new-privileges, process and memory limits).	Separate users per role are M7's work. Measured on straylight: rootless Podman 5.8.6 with crun, 40 to 80 ms per container.
2026-09-18	Tool containers run from one OCI image built by Nix (dockerTools) holding static toolkit, busybox, curl and the CA bundle, loaded with podman load and named by digest. No registry pull at call time. The owner's Gitea registry is the route when there is more than one host.	Pinned contents with no egress. Nix already builds the three binaries statically.
2026-09-18	http_fetch runs curl in a container with no network, through a per-call SOCKS5 proxy in its own container on a mounted Unix socket. The proxy is ours (in toolkit), accepts host names only, checks each against the grant's hosts, and copies bytes; TLS stays end to end in the tool container. clock moves into loopd.	No TLS stack of our own. Redirects are checked at the proxy. Measured on straylight 2026-09-18: allowed host 200 in 0.26 s; other host and IP literal refused.
2026-09-18	M2b: the baseline (system prompt, core tool schemas, memory/core.md) is snapshotted per epoch into sessions/<id>/<epoch>.baseline.json; resume uses the snapshot, so edits apply only to later sessions. The agent is called Boxmaker; the first system.md is drafted by the design model and edited by the owner. A Usage log record follows each Assistant record. bxctl chat shows reasoning dimmed by default. The core tool set is clock, find_tool, call_tool; echo is the first discoverable tool.	Owner's choices during the M2b design review; spec docs/specs/2026-09-18-m2b-agent-loop.md. Dimmed thinking shows progress and helps spot stalls.
2026-09-17	A compromised loopd can degrade the shared llama-server for other clients (large prompts, unpinned requests). Accepted for v0 and written into the threat model. inferproxy stays a byte forwarder with a connection cap and an accept-rate limit; it does not enforce slot or model policy. If isolation is wanted later, do it on the server side.	The harm is availability only, the owner would notice, and a policy proxy would put a parser for untrusted input into the component meant to have none.
2026-09-17	M2a limits: 10 min wait for a busy slot, 3 min for a model load, 30 s liveness after the first byte, thinking cap 4,096 tokens with max_tokens 8,192 as backstop. All are config values. The slot gate is held per request, never across a tool call.	Owner's choices during the M2a design review; measurements (j) to (n) in docs/inference-contract.md.
2026-09-17	SHA-256 comes from the owner's emsha crate, version 1.0.4 or later, not sha2 and not hand-written code in this repo. It is wrapped behind one function in proto, whose tests carry their own vectors: abc, the million-a message, and lengths 55, 56, 63, 64 and 65. The crate's custom licence is not an issue: the owner is its author.	No dependencies, no unsafe, no_std, owner-maintained. Version 1.0.3 hashed every message of length 63 mod 64 wrongly; a differential test against sha256sum found it while the crate was being vetted, and the owner fixed it in 1.0.4 (3,204 cases pass).
2026-09-17	M2 is split. M2a is the inference path (inferproxy, HTTP and SSE client, llama client, fake server, startup self-test). M2b is the agent loop (session log, turn loop, channel protocol, bxctl chat). Review happens after each.	The risky, timing-dependent work gets reviewed before the turn loop is built on it.
2026-09-17	Tool results are untrusted by default: each grant has untrusted, default true, and brokerd tracks a per-session untrusted flag beside taint. Review of Laguna's work is once per milestone, as an experiment for M1 to be revisited after the M1 review. Laguna keeps docs/implementer-log.md.	Owner's choices during the pre-M1 design review. Details in docs/specs/2026-09-17-pre-m1-design.md.
2026-09-17	Threat model: the main adversary is injected text steering the model. Secondary: any one role process or tool container is compromised, and the goal is containment. brokerd trusts nothing loopd reports beyond the request itself and tracks session taint on its own.	Owner's choice. It matches the role split the brief already has.
2026-09-17	Mattermost and the tailnet are trusted. A Mattermost compromise presumes the whole machine is compromised and is out of scope. Forged approvals are therefore out of scope, and there is no per-grant approval-path field. An accidental secret or PII leak into Mattermost is an accepted risk in v0.	Owner: Mattermost sits behind a single-user tailnet with ACLs.
2026-09-17	Data classes: every session starts at private. A secret result raises it to secret. public is a provenance label and never lowers a session. The grant that authorises a call names the class of its results (default private); tools never label their own output. A grant's allowed data classes are the highest session taint under which it applies. Unattended egress is controlled by grant mode, not by lowering the floor.	memory/core.md is in every baseline, so no session is really public. Job-scoped grants are left to M5.
2026-09-17	IPC: Unix stream sockets, strict JSON bodies in frames with a 4-byte length prefix and a size cap checked before allocation. Unknown fields rejected, tagged enums, no floats, golden-file fixtures as the wire spec. CBOR and protobuf were considered.	Every role needs a JSON parser anyway (llama-server, Mattermost, model-written tool arguments), so a binary envelope adds a parser without removing one. Both ends share the proto crate.
2026-09-17	Each daemon listens on one socket named after itself (infer.sock, broker.sock, loop.sock, gateway.sock). Peer authentication is by directory permissions per pair of roles. Blocking I/O with threads; no async runtime.	Small audited dependency tree, and fewer ways for the implementing model to go wrong.
2026-09-17	Audit and session logs stay JSONL. Type safety comes from the proto record types and strict decoding; the files are never built by string formatting. Writes go through one writer module so the format can change later.	Volume is one record per tool decision; fsync and inference dominate the cost by orders of magnitude.
2026-09-17	Boxmaker uses the shared llama-server router and the shared Ornith instance. No dedicated instance. inferproxy stays.	The owner runs coding agents against the same router, and a second resident copy of Ornith does not fit beside Laguna.
2026-09-17	The harness runs on straylight, the same host as llama-server.	Owner's choice. One host to secure, and no inference traffic crosses the tailnet.
2026-09-17	Container runtime is rootless Podman.	It is already the standard runtime on straylight and the owner's other hosts.
2026-09-17	Implementation is done by Laguna S 2.1, served by straylight, through OpenCode on the owner's development machine; builds are then deployed to straylight. Design, specs, measurement and review are done by a stronger model. Ornith-1.5-35B-A3B remains the model the harness serves.	The owner wants to test a local model on real implementation work. Plans must be written as small closed tasks with tests specified up front.
2026-09-17	M0 is run by the design model, not by Laguna.	M0 is measurement and interpretation, and its findings bind the design.

Open

Decision	Needed by
Thinking cap size. It starts at 4,096 tokens so that the right size can be found from data. From M2b every completion logs its reasoning-token count and whether the cap fired. Revisit once 200 completions are logged, or sooner if the owner sees answers cut short: raise the cap if more than 5% of completions hit it. Each hit also costs a re-read of that turn.	after M2b has run for a while
Repository licence. Crates are publish = false until it is chosen.	before publishing
Audit integrity beyond a self-contained hash chain (for example anchoring the chain head outside brokerd). Deferred by the owner on 2026-09-17 to a later revision.	after v0
Secret store backend, and where the v0 file's key lives. straylight has no secrets manager today. Moved from M3 on 2026-09-18.	M4
Whether cloud-led sessions are ever allowed, and for which data classes.	M6
Where the M5b embedding model runs. The brief says a separate llama-server instance, but under the shared router it would be a third model against --models-max 2 and could unload Ornith or Laguna. Owner's note, 2026-09-17: more compute is likely by then (possibly one to three DGX Spark machines), so do not design around today's memory limit.	M5b

Applied to the design brief

Approved by the owner on 2026-09-17. One commit each.

#	Change	Evidence
P1	Inference contract 6: the tools array is fixed per epoch. find_tool returns schemas as a tool result and the model calls them through a call_tool(name, arguments) meta-tool. Never instruct the model to call an undeclared tool.	M0 (h): adding a tool re-read the whole prompt; undeclared calls were coerced into write_file.
P2	Inference contract 2: the session log stores assistant messages exactly as returned, including reasoning_content, and replays them unchanged. Remove the "known risk" about dropped thinking blocks.	M0 (e): Ornith's template keeps every think block.
P3	Inference contract 7: requests set return_progress: true; progress events count as liveness.	M0 (i): otherwise the stream is silent during prefill.
P4	Inference contract 8: the thinking cap uses reasoning_control and the control endpoint.	README b10809. Exercised 2026-09-17, docs/inference-contract.md (k): it works, and a forced end costs a re-read of that one turn.
P5	Settle the open question: chat-completions with server-side tool parsing.	M0 (b), (c).
P6	Code constraints: Decision lives in brokerd, has a private field and does not implement Deserialize. proto carries a plain DecisionRecord for the audit log.	Rust privacy is per crate, and a deserializable type can be built by anyone.
P7	Inference contract 1: the baseline budget test needs the server's tokenizer, so make gate has an offline part and an on-device part (make verify-device).	/tokenize is a server endpoint.
P8	Target environment: describe the shared router as deployed (router mode, --models-max 2, other clients on the same Ornith instance, q8_0 KV, six-hour idle unload). Drop "memory is abundant".	docs/inference-contract.md, "What is running".
P9	Inference contract 5: slots are pinned with id_slot but not reserved. Another client can evict a harness slot, and the router can unload Ornith. Cache loss is an expected event: loopd detects it (cache_n far below the previous request's total), logs it in the session log, and carries on. It is never an error. A session always uses the same slot; threads may share the main slot.	Shared router decision. M0 (d): evicted sessions came back from the host-RAM prompt cache in under a second on the same slot, and cost a full re-read on another slot.
P10	Inference contract 7: a pinned request can queue behind another client's request on the same slot, and the router can spend tens of seconds reloading the model. The liveness timer starts at the first byte received, and a separate, longer "waiting for slot or model" limit covers the time before it.	Shared router decision. Measured 2026-09-17, docs/inference-contract.md (j): a queued request receives no bytes at all; /slots shows whether the slot is busy.
P11	Inference contract 10: the serving flags live in ~/src/nixos, not here. This repo records the expected values (template hash, per-slot n_ctx, slot count, KV type, sampling) and the startup self-test compares them with /props and /slots. KV type is recorded as q8_0.	Shared router decision.
P12	Network isolation 2: inferproxy is kept. Remove the conditional about dropping it. Its upstream is the router's TCP listener on the host.	Shared router decision; M0 (g).

Later changes to the brief:

Date	Change	Reason
2026-09-17	The roles table gained a one-sentence Purpose column, and the crates that are not roles got a purpose table under Code constraints. No behaviour changed.	Owner's request: a reader, human or agent, should learn what each piece is for before what it holds.

Proposed changes to the design brief

#	Change	Reason
P13	Authority contract 4: add "Tool containers run from one image built from source by Nix and named by digest; nothing is pulled at call time."	The brief does not say where tool images come from; a pull at call time would be unlisted egress. Decided 2026-09-18 above.