alkblobs/AGENTS.md

# AGENTS.md

Operating instructions for opencode agents working in this repo. opencode
auto-loads this file as instructions, overriding the built-in defaults for
this project. Custom agents in `.opencode/agents/` inherit these rules
unless their own prompts say otherwise.

## Git Workflow

**Commit and push when reasonable.** When a change is complete and
verified (build + lint + tests pass), commit and push to `origin/main`
without asking. This overrides the built-in default of "only commit when
explicitly asked."

The workflow:

1. Make the change
2. Verify: `cargo test`, `cargo clippy --all-targets -- -D warnings`,
   `cargo fmt --check`, `cargo doc --no-deps` if docs changed
3. Inspect `git status` and `git diff` before staging — stage only the
   intended files, never secrets
4. Write a concise commit message matching the repo style (see `git log
   --oneline -10`). For multi-point changes, use a summary line plus a
   body with bullet points and a verification block.
5. `git push origin main`
6. Report the commit hash and the verification summary

Exceptions — **do not** commit or push without asking:

- The change is exploratory / speculative (you're not sure the user wants
  it kept)
- The user is actively reviewing the diff and may ask for changes
- The change touches the wire format, a trait shape backends implement,
  or the hashing/verification story (one-way doors once consumers exist
  — see convention 7; nothing is wire-stable yet, but the first
  wire-format ADR must be written before the first consumer)
- You'd be force-pushing, amending a published commit, creating an empty
  commit, or skipping hooks

Never commit secrets, keys, or credentials. If a commit fails or hooks
reject it, fix the issue and create a new commit — do not amend the
failed one.

Git identity is preconfigured (`glm-5.3-flash <glm-5.3-flash@alk.dev>`). Do
not change `git config`, skip hooks, or use `git commit -i`.

## Project Conventions (Rust / blob storage crate)

This is the blob storage crate — content-addressed blob storage in the
alk* family, inspired by iroh-blobs' store work but deliberately not a
fork of it. It sits downstream of alkcall (the call + channels substrate
its network operations ride, when they exist) and its first planned
consumer is alkgit (git object storage, where the iroh-blobs hashing
story collides with git's own object hashes). Status: **Phase 0
(Exploration)** — `docs/research/` is the working state of the repo;
`docs/architecture/` does not exist yet and no wire format, API shape,
or backend trait is decided. The conventions below apply to all work in
`src/` and `tests/`. They mirror
`.opencode/agents/implementation-specialist.md` §Project Conventions and
are repeated here so they apply to every session.

1. **No comments in code** unless the user explicitly asks. This is a
   project-wide convention. Doc comments (`///`, `//!`) are fine and
   expected on public API. Inline `//` comments only when the user asks
   or when a non-obvious safety/correctness constraint would otherwise
   be missed.

2. **Error handling** — `thiserror` for library error types. No panics
   in library code. No `unwrap()` or `expect()` outside tests. If you
   reach for `unwrap`, the error path wasn't specified — stop and decide
   what should actually happen. For poisoned `RwLock`/`Mutex`, use
   `unwrap_or_else(|e| e.into_inner())` so a panic in one operation does
   not cascade to other operations.

3. **`tokio` is the async runtime** — all I/O is async. Use
   `tokio::sync` primitives (`oneshot`, `mpsc`) for lifecycle
   correlation; `parking_lot` for short-held internal locks. Do not
   introduce blocking I/O on the async path.

4. **Substrate-agnostic by construction** — the store layer must not
   know whether bytes arrive over the network, from a local writer, or
   get reassembled anywhere particular. iroh-blobs welds its store to
   its provider/ticket/postcard stack; this crate's defining posture is
   the opposite split: the store (put/get/verify against a hash) is its
   own layer, and transport/protocol concerns live above it or in
   feature-gated modules. This is the same inversion-point pattern as
   the alk* family (alktty `TtyBackend`, alktunnels pump halves).

5. **Canonical hash is the git-family derivation** — the store keys
   entries under git's oid derivation (`"blob <len>\0" + content`),
   SHA-256 canonically, SHA-1 tolerated (existing repos; git's own
   hardened-SHA-1 threat model inherited). The hash-conflict framing
   dissolved 2026-10-01: BLAKE3's presence was an iroh-blobs
   inheritance, not a requirement — it is demoted to a conditional
   large-blob encoding consideration (docs/research/phase-0.md
   OQ-BL-03). Do not hardcode beyond the small enum abstraction: the
   key encoding is a one-way door.

6. **Auth-gated operations ride the alkcall authorization seam** — when
   network-facing operations exist, authorization happens via alkcall's
   `AccessControl`/identity mechanisms (the producer/consumer model),
   not via an in-band invented auth scheme. Producer/consumer
   vocabulary, not "server"/"client" (alkcall ADR-022/037). Not yet
   pinned in detail — the ops surface is a Phase 0 question.

7. **Do not adopt iroh-blobs' wire surface** — tickets, the postcard
   serialization, and the provider protocol are iroh-blobs'
   design-welded choices we have decided not to inherit. Reading
   `/workspace/iroh-blobs` (a fresh upstream checkout) is encouraged for
   store-shape lessons (`src/store`, the kv + flat file backends);
   borrowing its *conclusions* is fine, wiring in its *types*, framing,
   or serialization as load-bearing dependencies is not (yet — the
   dependency posture is a Phase 0 question if a small pure piece, like
   bao outboard encoding, earns its place).

8. **Feature flags** — substrate backends (kv, sqlite, flat fs) may be
   feature-gated if the need arises. The base crate should compile lean.
   Verify both `cargo test` (default) and `cargo test --all-features`
   pass if features are added.

9. **Naming** — Rust standard: `snake_case` for functions/variables/
   modules, `PascalCase` for types/traits, `SCREAMING_SNAKE_CASE` for
   constants.

10. **Module structure** — one module per file under `src/`, re-exported
    from `src/lib.rs`. Public API surface is `lib.rs` re-exports. The
    expected shape (pending Phase 0 convergence) separates the
    backend/store layer from any protocol/ops layer.

## Verification Commands

Run these before committing. All must pass.

```bash
cargo test                                    # full suite
cargo clippy --all-targets -- -D warnings
cargo fmt --check
cargo doc --no-deps                           # if docs changed
cargo publish --dry-run --allow-dirty         # before a release
```

If feature flags are added, also run `cargo test --all-features` and
`cargo clippy --all-features --all-targets -- -D warnings`.

No fuzz targets exist yet for this crate. If/when a wire format is
pinned (Phase 1), a fuzz gate on the model of alkcall/alksocks (`fuzz/`
corpus replay on stable) is expected — until then ignore fuzzing.

## Architecture Context

- `docs/research/` — the Phase 0 (Exploration) state of this repo:
  research findings, POC records, and `phase-0.md` (vision, prior art,
  open questions, converged recommendation). Read it before non-trivial
  work. The SDD process lives in `docs/sdd_process.md`.
- `docs/architecture/` — does not exist yet (Phase 1 output). When it
  lands, the SDD process applies: specs describe WHAT, `decisions/`
  ADRs explain WHY, `open-questions.md` tracks what's unresolved.
- Key prior art (read-only, in the global workspace):
  - **iroh-blobs** — `/workspace/iroh-blobs` (fresh upstream checkout):
    the shape inspiration, specifically its store work (kv + flat file
    backends, bao verification, chunking). Its wire-surface choices
    (tickets, postcard, BLAKE3-only) are the ones we are deliberately
    diverging from.
  - **gix-odb** — `/workspace/git-oxide/gix-odb`: git's own object
    database; the backend alkgit currently plans against and the
    hashing-algorithm baseline git actually uses.
  - **alknet's blobs research** —
    `/workspace/@alkdev/alknet/docs/research/alknet-filesystem/`
    (`alknet-blobs-external-store-probe.md`, `poc-summary.md`): the
    appfile external-store probe — small blobs in a kv/sqlite-ish
    store, large blobs on the filesystem fallback, filename↔hash
    mapping. Written against an older iroh-blobs than the current
    checkout; re-verify conclusions before relying on them.
  - **alkcall** — `/workspace/@alkdev/alkcall` (the substrate):
    call + channels; its `AccessControl`/identity seam is the
    authorization story for network-facing blob ops.
- If a TODO references a design direction that a later ADR has decided
  against, the TODO is stale — remove it and align with the ADR. Do not
  implement the rejected design.