lance-graph-dir-sim: directory desired-state simulation over SoA + Quack (no writes)

[AdaWorldAPI]

This simulates a directory's future desired state before anything touches AD, Exchange or Entra:

observed G0 ──rule──► G1 ──rule──► G2 ──validate──► "desired" ──diff(G0,G2)──► ExecutionPlan ──X

This PR adds the execution half. The semantic vocabulary (Change, provenance, Violation, ExecutionPlan) lives in OGAR ogar-dir-sim, in AdaWorldAPI/OGAR#314. That PR must merge first, because this crate path-depends on the OGAR sibling. It follows the same pattern as lance-graph-report-ogar: excluded from the workspace, verified with cargo test --manifest-path crates/lance-graph-dir-sim/Cargo.toml. ndarray is a required dependency, pulled in through lance-graph-mask-risc.

How it is represented

• Snapshot: SoA lanes.
  • IDs are a Guid128 lane sorted so that a node's ordinal is its index. Ordinals are never used as identity.
  • Node kind and active status are bit planes.
  • UPN and SMTP are stored as dictionary ids, raw and normalized.
  • The OU-HHTL is a packed u64 lane.
  • Membership is a sorted (user, group) relation of u32 columns.
• A version is a shared Arc<Snapshot> plus a small overlay. The overlay holds added memberships, a bitmap of removed memberships and per-attribute overrides. The base snapshot is never copied.
• Every invariant is a Quack program:
  • Edge integrity is an anti-join (negate(Semijoin)), which lowers to two MaskOp::Gather ops over the node-kind planes.
  • SMTP and UPN uniqueness are GroupReduce Count keyed on a normalized-key dictionary id, run over the base and over the overlay and summed. The overlay's rows are admitted by a Semijoin against the active-user plane.
• No query's output can feed another query's Semijoin. The compiler enforces this.
  • A query's kept rows come back as Kept, whose only exit is rows(). Kept cannot be viewed as a plain slice, so it cannot be passed as another query's join input.
  • A compile_fail doctest pins this, alongside a twin doctest that does compile. The guard was checked by temporarily giving Kept a slice view: the compile_fail doctest then failed.
  • Every join input in the crate is a stored plane: the user plane, the group plane or the active-user plane.
• Population rules combine two folded GROUP BY sinks at the caller. The sinks are sized by the node universe, not by membership rows. There are no per-user workflow loops.
• ogar-loco is not used for rules yet. The only loco dialect that lowers to mask-risc (FoldDialect) lives inside a test file in r2il-mask-abi-probe, not in a library. It also keeps only the last GROUP_SUM result, so it cannot hold ImplyGroup's two per-user counts. Copying it here would add a second arity table. This is listed under Open below.
• HHTL as geometry: selecting an OU subtree is a single Cmp::MatchU64 prefix match. No DN strings are involved.

Measured

tests/alloc.rs counts bytes allocated for one simulated membership change:

one membership mutation	1k users	100k users
simulate	853 B	853 B
same-root diff	1,208 B	1,208 B

Verification

All runs use CARGO_PROFILE_DEV_DEBUG=0 CARGO_INCREMENTAL=0.

• 23 tests and 2 doctests pass. They cover all 17 required properties, plus:
  • the rejected SMTP collision;
  • the audit chain (G0 → ExchangeAccess/v1 → G1);
  • convergence of a re-observed state;
  • removal and re-add;
  • OU subtree selection;
  • observation from ogar-ad records;
  • a falsifier that renaming a user away from a colliding address clears the collision.
• clippy -D warnings and fmt are clean. No unsafe in the library; the test allocator's two unsafe calls are documented.
• Disable-runs. Each of these eleven guards was disabled in turn; each made its test fail, and all pass again with the guards restored:
  • the group-side anti-join;
  • the semijoin lowering;
  • the uniqueness HAVING > 1;
  • overlay values being counted;
  • an override replacing the base value;
  • the promotion gate;
  • the compare-and-set precondition;
  • the population "minus target" step;
  • the delta-path diff, checked with the allocation test;
  • GUID-sorted ordinals;
  • the Kept seal.

Open (also recorded in the board entry)

• VersionedGraph cannot persist 128-bit directory identity: its node ids are u32 and its diff only reports additions. It needs either a wider upstream type or a dedicated directory dataset.
• Creating or deleting nodes is not in the Change algebra yet.
• The packed OU lane handles prefixes up to depth 4 exactly and refuses deeper ones.
• To write rules as ogar-loco programs, a fold dialect first has to move into a library, and it must keep each GROUP_SUM result instead of only the last one.

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https://claude.ai/code/session_01G22yT6htkcdyXsihxxXdrg

Summary by CodeRabbit

• New Features

  • Added directory-state simulation to propose and track membership and email-address changes across versions.
  • Added validation for missing membership endpoints and duplicate active-user UPN or primary SMTP addresses.
  • Added change summaries, execution planning, membership history explanations, and OU-subtree selection.
  • Added safeguards that prevent promotion to desired state when validation finds issues.

• Tests

  • Added coverage for simulation, validation, planning, and directory observation, including checks that allocation remains bounded as directory size grows.

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📝 Walkthrough

Walkthrough

Adds a standalone Rust crate for directory desired-state simulation over SoA snapshots and Quack. It converts directory observations, applies rule proposals through overlays, validates membership and attribute constraints, and manages version history, diffs, and plans.

Changes

Directory simulation

Layer / File(s)	Summary
Observation and snapshots Cargo.toml, crates/lance-graph-dir-sim/Cargo.toml, crates/lance-graph-dir-sim/src/{lib,snapshot,observe}.rs, crates/lance-graph-dir-sim/tests/sim.rs	Adds the standalone crate, AD-record conversion, snapshot lanes and lookup, OU subtree selection, and tests for directory observation and subtree behavior.
Snapshot-backed views and validation crates/lance-graph-dir-sim/src/{view,exec,rule,validate}.rs, crates/lance-graph-dir-sim/tests/sim.rs	Adds overlay-backed views, change application, Quack execution helpers, membership and SMTP rules, and validation for dangling memberships and duplicate normalized attributes. Tests cover validation, collision handling, and overlay behavior.
Version lifecycle, diffs, and plans crates/lance-graph-dir-sim/src/store.rs, crates/lance-graph-dir-sim/tests/{sim,alloc}.rs, .claude/board/entries/{2026-10-03-dir-sim-soa-quack.md,README.md}	Adds version storage, simulation, validation-based desired promotion, diffs, plans, and membership explanations. Tests cover lineage, planning, convergence, and allocation bounds. The board entry records design notes and measurements.

Priority: ➖ Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant VersionStore
  participant Rule
  participant View
  participant Validator
  VersionStore->>View: Reconstruct parent view
  VersionStore->>Rule: Request changes from view and evidence
  Rule-->>VersionStore: Return proposed changes
  VersionStore->>View: Apply proposed changes
  VersionStore->>Validator: Validate version
  Validator-->>VersionStore: Return violations
  VersionStore->>VersionStore: Promote when validation has no violations

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Merge Risk: ⚪ Minimal · up to 9a2ca

This change adds an isolated simulation crate that does not write to the directory systems. No concrete merge-blocking risk was found in the reviewed changes. The author notes that the OGAR sibling PR must merge first, which is a sequencing matter rather than a code defect.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 73.68% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 114 functions across 10 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely identifies the directory desired-state simulation and its use of SoA and Quack. The no-writes scope is also stated.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Inline comments:
Review comments at @crates/lance-graph-dir-sim/src/store.rs:
- Around line 221-224: Update plan() where it maps errors from diff(basis,
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📒 Files selected for processing (14)

• .claude/board/entries/2026-10-03-dir-sim-soa-quack.md
• .claude/board/entries/README.md
• Cargo.toml
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• crates/lance-graph-dir-sim/src/exec.rs
• crates/lance-graph-dir-sim/src/lib.rs
• crates/lance-graph-dir-sim/src/observe.rs
• crates/lance-graph-dir-sim/src/rule.rs
• crates/lance-graph-dir-sim/src/snapshot.rs
• crates/lance-graph-dir-sim/src/store.rs
• crates/lance-graph-dir-sim/src/validate.rs
• crates/lance-graph-dir-sim/src/view.rs
• crates/lance-graph-dir-sim/tests/alloc.rs
• crates/lance-graph-dir-sim/tests/sim.rs

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