mr-668: composite e2e tests, race fix, v0.7.0 release (PR 9/10)

PR 9 — the final integration PR for MR-668 multi-graph server work.
Closes the v0.7.0 release.

Composite lifecycle tests (closes gaps flagged in PR 7's coverage
review):
  - `multi_graph_lifecycle_post_query_restart_persistence` — POST a
    graph, query it via cluster route, reload the config from disk
    and confirm `load_server_settings` sees the rewritten YAML.
    Validates the "restart resolves orphans" failure-mode story.
  - `per_graph_policy_enforced_on_post_created_graph` — POST a graph
    with a per-graph policy attached, then send authenticated read
    and change requests. Per-graph Cedar enforcement fires correctly
    on a POST-created graph (engine-layer policy reinstalled via
    `Omnigraph::with_policy` inside the create flow).
  - `concurrent_post_graphs_distinct_ids_all_succeed` — 4 concurrent
    POSTs with distinct graph_ids all return 201. Caught a real
    race in `rewrite_atomic` (see below).

Race fix — `rewrite_atomic_with_modify`:

The first composite test surfaced a real bug. The old
`rewrite_atomic(path, new_config, expected_hash)` captured the
baseline hash OUTSIDE the flock, then called rewrite_atomic which
re-acquired it inside. Under concurrent writers:

  - POST A: captures baseline H0, calls rewrite_atomic.
  - POST B: captures baseline H0 too (before A's update lands).
  - A: acquires flock, on-disk == H0, writes H1, releases.
  - A: updates baseline H0 → H1.
  - B: tries to acquire flock — waits.
  - B: acquires flock. On-disk is now H1. Expected (captured
       before A finished) is H0. MISMATCH → spurious Drift error.

Worse: even if the timing happens to align, B's `updated` config
was constructed from BYTES read before the flock. B writes a config
that doesn't include A's new graph — silent data loss.

The fix: new `config::rewrite_atomic_with_modify(path, baseline,
modify)` takes a closure. Inside the flock + baseline mutex:
  1. Read on-disk bytes, hash, compare to baseline.
  2. Parse on-disk YAML.
  3. Call `modify(parsed)` to produce the new config — receives
     fresh on-disk state, returns the modification.
  4. Serialize + write + fsync + rename + update baseline.

Everything is read-modify-write under the same critical section.
Concurrent writers serialize cleanly. Test confirmed this is no
longer a race.

The old `rewrite_atomic(path, new_config, expected_hash)` API stays
for tests that don't need the read-modify-write shape; the POST
handler switches to the new shape.

Version bump v0.6.0 → v0.7.0:
  - All 5 `crates/*/Cargo.toml` (compiler, engine, policy, cli, server)
    plus their inter-crate `path` dep version constraints.
  - `Cargo.lock` regenerated by `cargo build --workspace`.
  - `AGENTS.md` "Version surveyed" line, capability matrix HTTP-server
    row updated to mention multi-graph + cluster routes + atomic YAML
    rewrite.
  - `openapi.json` regenerated.

Docs:
  - `docs/releases/v0.7.0.md` (new) — release notes with breaking
    changes, new features, deferred items (DELETE, `delete_prefix`,
    actor forwarding), and the single→multi migration recipe.
  - `docs/user/server.md` — substantial section additions for the
    two modes, mode inference, cluster endpoint table, management
    endpoints, `omnigraph.yaml` ownership contract, `POST /graphs`
    body shape + status codes.
  - `docs/user/cli.md` — `omnigraph graphs list/create` section,
    deferred-DELETE note.
  - `docs/user/policy.md` — server-scoped Cedar actions
    (`graph_create`, `graph_list`), per-graph vs server-level policy
    composition, example server-level policy.

Workspace test pass: 573 tests green across all crates. Zero
failures. MR-731 spoof regression still pinned and passing across
the entire 10-PR series.

This commit closes MR-668. v0.7.0 is ready for tagging.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -16,8 +16,8 @@ Tools that support `@`-imports (Claude Code) auto-include all three files via th
 
 `CLAUDE.md` is a symlink to this file — there is exactly one source of truth. Edit `AGENTS.md`.
 
-**Version surveyed:** 0.6.0
-**Workspace crates:** `omnigraph-compiler`, `omnigraph` (engine), `omnigraph-cli`, `omnigraph-server`
+**Version surveyed:** 0.7.0
+**Workspace crates:** `omnigraph-compiler`, `omnigraph` (engine), `omnigraph-policy`, `omnigraph-cli`, `omnigraph-server`
 **Storage substrate:** Lance 6.x (columnar, versioned, branchable)
 **License:** MIT
 **Toolchain:** Rust stable, edition 2024
@@ -33,7 +33,7 @@ OmniGraph is a typed property-graph engine built as a coordination layer over ma
 - **Multi-modal querying**: vector ANN (`nearest`), full-text (`search`/`fuzzy`/`match_text`/`bm25`), Reciprocal Rank Fusion (`rrf`), and graph traversal (`Expand`, anti-join `not { … }`) in one runtime.
 - **Branches and commits across the whole graph**: Git-style — every successful publish appends to a commit DAG; merges are three-way at the row level.
 - **Atomic per-query writes**: `mutate_as` and `load` accumulate insert/update batches into an in-memory `MutationStaging.pending` per touched table; one `stage_*` + `commit_staged` per table runs at end-of-query, then `ManifestBatchPublisher::publish` commits the manifest atomically with per-table `expected_table_versions` CAS. A mid-query failure leaves Lance HEAD untouched on staged tables — no drift, no run state machine, no staging branches. Deletes still inline-commit; D₂ at parse time prevents inserts/updates and deletes from coexisting in one query.
-- **HTTP server**: Axum + utoipa OpenAPI, bearer auth (SHA-256 hashed, optional AWS Secrets Manager). Cedar policy enforcement is engine-wide — every `_as` writer calls `Omnigraph::enforce(action, scope, actor)`, so HTTP, CLI, and embedded SDK consumers all hit the same gate.
+- **HTTP server**: Axum + utoipa OpenAPI, bearer auth (SHA-256 hashed, optional AWS Secrets Manager). Cedar policy enforcement is engine-wide — every `_as` writer calls `Omnigraph::enforce(action, scope, actor)`, so HTTP, CLI, and embedded SDK consumers all hit the same gate. **Two modes** (v0.7.0+): single-graph (legacy flat routes) and multi-graph (`/graphs/{graph_id}/...` cluster routes + `POST/GET /graphs` management endpoints with atomic YAML rewrite + drift detection). Per-graph + server-level Cedar policies.
 - **CLI** driven by a single `omnigraph.yaml`; multi-format output (json/jsonl/csv/kv/table).
 
 Throughout the docs, capabilities are split into **L1 — Inherited from Lance** vs **L2 — Added by OmniGraph**.
@@ -227,7 +227,7 @@ omnigraph policy explain --actor act-alice --action change --branch main
 | Three-way row-level merge | — | `OrderedTableCursor` + `StagedTableWriter`, structured `MergeConflictKind` |
 | Change feeds | — | `diff_between` / `diff_commits` with manifest fast path + ID streaming |
 | Cedar policy | — | 8 actions, branch / target_branch / protected scopes, validate/test/explain CLI. **Engine-wide enforcement** (MR-722): every `_as` writer (`apply_schema_as`, `mutate_as`, `load_as`, `ingest_as`, `branch_create_as` / `branch_create_from_as`, `branch_delete_as`, `branch_merge_as`) calls `Omnigraph::enforce(action, scope, actor)` — HTTP, CLI, embedded SDK all hit the same gate. |
-| HTTP server | — | Axum, OpenAPI via utoipa, bearer auth (SHA-256, AWS Secrets Manager option), `authorize_request` at the HTTP boundary (resolves bearer→actor, applies admission control), NDJSON streaming export |
+| HTTP server | — | Axum, OpenAPI via utoipa, bearer auth (SHA-256, AWS Secrets Manager option), `authorize_request` at the HTTP boundary (resolves bearer→actor, applies admission control), NDJSON streaming export, **multi-graph mode (v0.7.0+) with cluster routes + `POST/GET /graphs` management endpoints + atomic YAML rewrite under `fs2::flock` + SHA-256 drift detection** |
 | CLI with config | — | `omnigraph.yaml`, aliases, multi-format output (json/jsonl/csv/kv/table) |
 | Audit / actor tracking | — | `_as` write APIs + actor map in commit graph |
 | Local RustFS bootstrap | — | `scripts/local-rustfs-bootstrap.sh` one-shot S3-backed dev environment |