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 | Spec review of M3a, approvals. The approval block in `bxctl chat` is fetched from `brokerd` by id, never taken from `loopd`'s event. It shows the parsed arguments serialised again, with control, invisible and direction-changing characters as `\uXXXX`. The owner types the approval id, not `y`. `bxctl chat` escapes model text the same way. A `tool_denied` turn event carries the reason to the owner. | A compromised `loopd` must not choose what the owner approves; `/etc` and `/etc` must look alike; U+202E can make a path read as another; a line already waiting in stdin must never approve; `chat` wrote model text raw, so a conceal sequence could hide the block. |
| 2026-09-18 | Spec review of M3a, `brokerd` internals. One lock (the ledger) covers the audit writer and the session state files; the pending table has its own, and whoever removes an entry answers it. After any failed audit write, `brokerd` denies with `audit_unavailable` until restarted. `policy` is pure, and `decide` never returns a `Decision` for an `ask` grant: only `redecide` turns an `Ask` into one. A `RunError`'s text is fixed text, never tool output, and a failure does not raise taint. `BrokerPort` waits `[broker] timeout_ms` for a first frame, and until `expires` plus that after a pending one. | Without the lock two results could lower a session's taint. A partial line followed by more records is a broken chain. `loopd` logs failures as `public`, so tool output in one would be unlabelled. |
| 2026-09-18 | Spec review of M3a, policy. A `deny` grant must have `max_taint = "secret"` or the grant set is invalid. A result's `result_class` and `untrusted` are combined over every matching grant (highest class; untrusted if any says so), and within a mode the grant with the longest matched path wins before the id tie-break. A grant path of `/` is invalid. | A `deny` grant with a lower `max_taint` stopped denying once the session read a secret. With overlapping `auto` grants the id tie-break chose the label, so a secret could come back `private`. M3b mounts grant paths at the same path, where `/` would replace the tool image. |
| 2026-09-18 | Spec review of M3a, audit. A line followed by a matching `Recovery` is recovered whether or not it parses; an unparseable last line is recovered like a torn one. The writer never moves to an earlier day's file, and `Recovery` and `AcceptedBreak` go in the latest file. `--accept-break` verifies the whole log; the verifier checks an `AcceptedBreak`'s `file`, `line`, `last_good`, `prev` and `seq`, and the `seq` is counted from lines, not read from them. The `Approval` record carries the re-decision's grant and session state. The report lists allowed calls with no `Result`. | As first written, a record cut exactly before its newline made `brokerd` break its own chain; so did a clock stepped back over midnight; a break in an older file could never be accepted; and a damaged line could choose the next `seq`. |
| 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 |
| How an approval whose arguments do not fit one Mattermost post is shown. Settled on 2026-09-18: what is being approved is never truncated, in any channel, because the unseen tail is where injected text would put its payload; `bxctl` prints arguments in full. Leading option for Mattermost: a thread of numbered chunks split on character boundaries of the escaped text, where only a reply or reaction on the last post counts and that post repeats the id, the chunk count and the hash of the whole; above some number of chunks, the post points to `bxctl approvals` and approval is local only. The post size limit and rate limits must be checked against the Mattermost API reference first. | M4 |
| 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. |
| 2026-09-18 | P14, State: the list gained `broker/sessions/<id>.json`, each session's taint and untrusted flag, written only by `brokerd`. | The M3a spec keeps this state in files the list did not name. It can be rebuilt from the audit log's `result` records, so the audit log stays the record of truth. Owner: a plain file also makes debugging easier. |

## 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. |