---
status: draft
last_updated: 2026-09-25
---

# alkgit Architecture

Phase 1 (SDD) output for alkgit — the git payload service of the alk
family: a pure protocol crate on alkcall channels (the `alk/git` ALPN),
following the alktty/alktunnels template (ADR-010). Phase 0 research lives
in [docs/research/](../research/README.md); every design claim here traces
to a POC finding or research doc, or is flagged as an open question.

## Current State

Phase 1, architecture committed to the pure-protocol-crate shape (ADR-010;
OQ-09 resolved). POC-1/2/3 validated the git protocol half end-to-end
against real git 2.43. Previous cycles settled the auth/backend theme
(ADR-011, ADR-012). This cycle settled the wire surface against
real-client captures: the receive-pack push state machine (ADR-013,
OQ-04) and the V2 multi-round negotiation ack loop (ADR-014, OQ-02). All
wire-layer design is now capture-grounded; the remaining open questions
are the publish-freeze timing (OQ-03, a release decision), sha256
policy (OQ-05, deferred on ecosystem need), and the grant-key identity
namespace (OQ-16, deferred on the first cross-assembly deployment —
blocks nothing in v1). ADR-015 resolved
review 001's A-1 (the repo-op gate) with the `manage` grant tier.

## Architecture Documents

| Doc | Area | Status |
|---|---|---|
| [overview.md](overview.md) | Cross-cutting: crate shape, halves, security invariants | draft |
| [transport.md](transport.md) | Wire layer: substrates, V2 state machines, upload/receive-pack | draft |
| [backend.md](backend.md) | Backend traits + feature-gated gix implementation | draft |
| [doors.md](doors.md) | Door mappings: alkhttp `git` feature, alkssh requirement, native path | draft |
| [open-questions.md](open-questions.md) | Centralized OQ tracker | — |

## ADRs

| ADR | Decision | Status |
|---|---|---|
| [001](decisions/001-crate-decomposition.md) | Workspace crate decomposition (5 crates) | Superseded (ADR-010) |
| [002](decisions/002-front-door-blind-core.md) | Session boundary (identity, repo, stream, limits) | Accepted |
| [003](decisions/003-protocol-v2-first.md) | Protocol V2-first with honest capability advertisement | Accepted |
| [004](decisions/004-pack-pipeline.md) | Pack pipeline (`data::output` gen / `data::input` ingestion) | Accepted |
| [005](decisions/005-session-substrate-types.md) | Session substrate types (duplex + stateless APIs) | Accepted |
| [006](decisions/006-http-adapter-composition.md) | HTTP adapter composition (alkgit-owned router factory) | Superseded (ADR-010) |
| [007](decisions/007-acl-before-advertisement.md) | ACL runs before any advertisement/ref line | Accepted |
| [008](decisions/008-registry-resolved-repo-identity.md) | Wire repo names are registry IDs, never paths | Accepted |
| [009](decisions/009-bounded-resources-budget.md) | Bounded-resources budget model | Accepted |
| [010](decisions/010-pure-protocol-crate.md) | Pure protocol crate (alktty/alktunnels template) | Accepted |
| [011](decisions/011-per-repo-authorization.md) | Per-repo authorization (grants in records, policy in core) | Accepted |
| [012](decisions/012-registry-backing-and-ops.md) | Registry backing, write surface, CRUD ops, feature split | Accepted |
| [013](decisions/013-receive-pack-state-machine.md) | receive-pack state machine (V0-framed push, thin-pack, unpack-first CAS) | Accepted |
| [014](decisions/014-v2-negotiation-ack-loop.md) | V2 negotiation ack loop (no `ready`, wait-for-done stays) | Accepted |
| [015](decisions/015-manage-grant-and-op-gate.md) | Manage grant tier + repo-op gate (admin scope OR manage grant) | Accepted |

## Open Questions

All unresolved questions are tracked in [open-questions.md](open-questions.md)
with stable OQ-IDs, priorities, and cross-references. Remaining: OQ-03
(publish freeze inventory — partially resolved, blocked on first-publish
timing), OQ-05 (sha256, deferred on ecosystem need), and OQ-16 (grant-key
identity namespace, deferred on the first cross-assembly record-sharing
deployment). The wire-layer
questions (OQ-02, OQ-04) resolved this cycle with ADR-014/ADR-013.

## Document Lifecycle

| Status | Meaning | Transitions |
|---|---|---|
| `draft` | Under active development; may change significantly | → `reviewed` when its OQs are resolved |
| `reviewed` | Architecture final; implementation may begin; changes need review | → `stable` when implementation verified |
| `stable` | Locked; changes require review, may warrant an ADR | → `deprecated` when superseded |
| `deprecated` | Superseded; kept for reference | Removed when no longer referenced |