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All eight comments verified against source and applied:
- AGENTS.md: pull @docs/{invariants,lance,testing}.md imports out of
the markdown blockquote. Claude Code's @-import parser expects @ at
column 0; the leading "> " of a blockquote silently broke
recognition, so the claimed auto-include did nothing. (Cursor,
Medium severity.)
- docs/cli-reference.md: command-family count 13 → 17. The current
enum Command in crates/omnigraph-cli/src/main.rs has 17 top-level
variants. (cubic P2.)
- docs/ci.md: Homebrew tap update is a regular `git push`, not a
force-push (release.yml:117 is `git push origin HEAD:main`). (cubic
P2.)
- docs/errors.md: add the Storage variant to the NanoError list — it
exists at error.rs:88-89 but the doc enumerated only 10 of 11.
(cubic P2.)
- docs/storage.md: clarify tombstone semantics. There is no
tombstone_version column; state.rs:180 reads the tombstone version
from the table_version column on rows where object_type =
table_tombstone. (cubic P2.)
- docs/branches-commits.md: split the GraphCommit pseudo-struct from
the underlying storage. actor_id is joined in-memory from
_graph_commit_actors.lance, not a column on _graph_commits.lance.
(cubic P2.)
- docs/schema-language.md: rename IR_VERSION to SCHEMA_IR_VERSION to
match the actual constant name in catalog/schema_ir.rs:11.
(cubic P3.)
- docs/testing.md: engine integration test count 16 → 15 (matches
`ls crates/omnigraph/tests/*.rs`). (cubic P3.)
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
57 lines
2.8 KiB
Markdown
57 lines
2.8 KiB
Markdown
# Branches, Commits, Snapshots
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## L1 — Lance per-dataset branches
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Lance supports branching at the dataset level: a branch is a named lineage of versions, and `fork_branch_from_state(source_branch, target_branch, source_version)` creates a copy-on-write fork.
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## L2 — Graph-level branches
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OmniGraph builds *graph branches* on top by branching every sub-table coherently:
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- `branch_create(name)` / `branch_create_from(target, name)` — disallowed name `main`; fails if branch exists; ensures the schema-apply lock is idle.
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- `branch_list()` — returns public branches, **filters internal** `__run__…` and `__schema_apply_lock__` prefixes.
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- `branch_delete(name)` — refuses if there are descendants or active runs on the branch; cleans up owned per-branch fragments.
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- **Lazy forking**: a branch only forks a sub-table when that sub-table is first mutated on it. Pure-read branches share fragments with their source.
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- `sync_branch(branch)` — re-binds the in-memory handle to the latest head of the branch.
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## L2 — Commit graph (`db/commit_graph.rs`)
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In-memory shape of a graph commit:
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```
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GraphCommit {
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graph_commit_id: ULID,
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manifest_branch: Option<String>,
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manifest_version: u64,
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parent_commit_id: Option<String>,
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merged_parent_commit_id: Option<String>, // populated for merge commits
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actor_id: Option<String>, // joined in-memory from _graph_commit_actors.lance, NOT a column on _graph_commits.lance
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created_at: i64 (microseconds since epoch),
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}
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```
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Storage is split across two Lance datasets (both with stable row IDs):
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- `_graph_commits.lance` — every column above *except* `actor_id`.
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- `_graph_commit_actors.lance` — optional separate `(graph_commit_id, actor_id)` map, created on demand. The `actor_id` field above is populated by joining this dataset in-memory at load time.
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Notes:
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- Every successful publish (load / change / merge / schema_apply / publish_run) appends one commit.
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- Merge commits have two parents; linear commits have one.
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- API: `list_commits(branch)`, `get_commit(id)`, `head_commit_id_for_branch(branch)`.
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## L2 — Snapshots & time travel
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- `snapshot()` — current snapshot for the bound branch; cached.
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- `snapshot_of(target)` — snapshot at a `ReadTarget` (branch | snapshot id).
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- `snapshot_at_version(v: u64)` — historical snapshot from any manifest version.
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- `entity_at(table_key, id, version)` — single-entity time travel without building a full snapshot.
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- A `Snapshot` is a `(version, HashMap<table_key, SubTableEntry>)` — cheap to build, snapshot-isolated cross-table reads.
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## L2 — Internal system branches
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Filtered from `branch_list()` but visible to internals:
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- `__run__<run-id>` — ephemeral isolation branch for a transactional run.
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- `__schema_apply_lock__` — serializes schema migrations.
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