expand_less
**Hyperon Experimental** is the official trueagi-io Rust reference implementation of the MeTTa runtime. At HEAD `3f76dc46` (v0.2.10, 2026-02-11), it is the foundational MeTTa runtime substrate that all alternative MeTTa runtimes either port, transpile, embed, or bridge.
## Source Identity
- Origin:
- HEAD pinned: `3f76dc460da6961f57f69f6c3e550c59c74ada83`
- Tagged release: v0.2.10 (Merge PR #1075, 2026-02-11, Vitaly Bogdanov)
- Tag timeline: v0.2.1 (2024-10-23) → v0.2.10 (2026-02-11), 10 minor releases over ~16 months
- 7-crate Rust workspace: `hyperon-common`, `hyperon-atom`, `hyperon-space`, `hyperon-macros`, `lib`, `c`, `repl`
- Non-workspace dirs: `python/` (pybind11 bindings + sandbox), `integration_tests/das/`, `docs/`
- Tracked-file inventory: 296 files (85 .rs + 67 .metta + 65 .py + 22 .md + smaller)
- Primary maintainer: Vitaly Bogdanov (2,137 commits all-time)
## Architecture
### Interpreter Semantics
`[SMALL-STEP-INTERPRETER]` `[NONDETERMINISTIC-BRANCHING]`
Stack-based, plan/state-driven, nondeterministic. **NOT** a deterministic "first match wins" rewrite engine — multiple matches produce multiple results. Key entry points in `lib/src/metta/interpreter.rs`:
- `interpret_step` (L269) — main reduction step
- `interpret_stack` (L374) — stack dispatch with depth enforcement (L392)
- `eval_impl` (L504), `eval_result` (L559), `query` (L604)
- `chain` (L687), `collapse-bind` (L746), `unify` (L809), `superpose-bind` (L893)
- Native grounded-symbol calls (L922)
**Boundary**: programs requiring deterministic dispatch must use mutually exclusive patterns. Catchall equations (`$_`, `$other`) alongside specific equations produce multiple reductions — this is documented language semantics, not a defect.
### Type System
`[DYNAMIC-CHECKED]`
`lib/src/metta/types.rs`:
- `%Undefined%` is permissive wildcard — assigned to atoms without a user type, matches any required type (L18-19)
- `check_arg_types` (L65), `get_atom_types` (L327), `get_application_types` (L512), `UndefinedTypeMatch` (L526)
- `check_type` (L602), `validate_atom` (L637)
- Dependent-type tests at L817, L861, L1120, L1139
- Open TODOs at L42, L379, L397, L494-499, L1177, L1225, L1298
Hyperon Experimental supports expressive type checking, but should **NOT** be described as a fully-settled categorical/dependent-type verifier.
### Standard Library
`[HYBRID-RUST-PLUS-METTA-STDLIB]`
Split between Rust-side token registrations under `lib/src/metta/runner/stdlib/` and MeTTa-side definitions in `stdlib.metta` (1,421 lines). Cross-runtime audits **must** cover both layers.
Rust-side modules:
- `arithmetics.rs` (L162-198): `+`, `-`, `*`, `/`, `%`, ``, `=`, `and`, `or`, `not`, `xor`, division
- `atom.rs` (L449-474): `unique-atom`, `union-atom`, `intersection-atom`, `max-atom`, `min-atom`, `size-atom`, `index-atom`, `subtraction-atom`, `get-type`, `get-metatype`, `get-type-space`
- `core.rs` (L336-362): `pragma!`, `nop`, `sealed`, `==`, `match`, `if-equal`, `superpose`, `capture`, `_minimal-foldl-atom`
- `debug.rs` (L155-177): `trace!`, `print-alternatives!`, `=alpha`
- `math.rs` (L408-443): `pow-math`, `sqrt-math`, `abs-math`, `log-math`, etc., plus `PI` and `EXP` constants
- `module.rs` (L280-298): `import!` (L290), `include`, `mod-space!`, `print-mods!`, `bind!` (L269), `module-space-no-deps`
- `package.rs` (L113-117): `register-module!`, `git-module!`
- `space.rs` (L206-223): `new-space`, `get-state`, `change-state!`, `get-atoms`, `add-atom`, `remove-atom`
MeTTa-side definitions in `stdlib.metta`: `return` (L47), `function` (L54), `eval` (L61), `chain` (L78), `unify` (L88), `cons-atom` (L96), `decons-atom` (L103), `collapse-bind` (L239), `superpose-bind` (L246), `metta` (L255), `switch` (L345-362), `if` (L511-513), `let`/`let*` (L542-553), `collapse` (L1203), `case` (L1224-1233).
**NOTE**: there is **NO** `replace-atom!` MeTTa op at HEAD. PATCH-2 from the AtomSpace Integration Phase 4 cluster pilot recommends adding it.
### Built-in Modules
`[BUILTIN-FULLY-WIRED]`
`lib/src/metta/runner/builtin_mods/mod.rs` registers six loaders:
- `random`, `skel`, `fileio`, `json`
- `catalog` (`pkg_mgmt` Cargo feature)
- `das` (`das` Cargo feature, default-enabled per `lib/Cargo.toml:46`)
Each module pairs a `.rs` registration file with a `.metta` doc file (`catalog.metta`, `das.metta`, `fileio.metta`, `json.metta`, `random.metta`, `skel.metta`).
DAS is available as a default feature and builtin module surface, but does **NOT** mean a running distributed DAS service is embedded in the local runtime — `metta-bus-client` connects to a remote DAS service.
### Module System
`[MODULE-SYSTEM-PARTIAL]`
Implemented and active but evolving (per `docs/modules_internal_discussion.md`'s "poor man's" public/private scope concept).
`lib/src/metta/runner/modules/mod.rs`:
- `ModId` (L27), `MettaMod` (L56), resource and loader fields (L58, L62)
- `import_dependency_as` (L107), `import_item_from_dependency_as` (L131), `import_all_from_dependency` (L181)
- Accessors path/name/package/space/tokenizer/resource (L251-278)
- Descriptor state (L314), module init (L439), `ModuleLoader` trait (L563), `Resource` (L608)
- Name resolution at `mod_names.rs:265` and `:276`
Imports via `import!` (registered at `stdlib/module.rs:290`) create separate `DynSpace` instances.
### AtomIndex / AtomTrie
`[IN-MEMORY-ATOMTRIE-INDEX]` `[NO-BENCHMARK-CLAIMS]`
`hyperon-space/src/index/`:
- `AtomIndex` (`mod.rs:159`), insert (`:177`), query (`:192`), remove (`:207`)
- `AtomTrie` (`trie.rs:201`, 930 lines), insert (`:232`), query (`:261`), remove (`:395`)
Concentrated implementation period 2025-01-31 → 2025-02-11 (initial implementation, GroundingSpace integration, duplication strategy parameter, AtomStorage/AtomTrieNode separation, compactness improvements). Size-prefix optimization landed at `120c2279` (2025-08-26) — *"Prefix expressions with size in atomspace index to recognize them faster"*.
**NO** quantitative scaling ceilings claimed at this time. Existing benches at `hyperon-space/benches/atom_index.rs` and `lib/benches/grounding_space.rs` operate at 100/x10/x100 atom scales only. An empirical bench harness is required for any production scaling claims.
### Hyperon Space Write API and Observer Pattern
(Phase 4 prior art — re-confirmed at HEAD)
The Hyperon Space write surface is complete at the Space/C/Python layers:
- `SpaceMut::add` / `remove` / `replace` at `hyperon-space/src/lib.rs:237/255/275`
- `GroundingSpace ` concrete impl at `lib/src/space/grounding/mod.rs:14-21`; inherent `add`/`remove`/`replace` at `:70/:92/:119`
- C-API write surface at `c/src/space.rs:140-143`; observer registration at `c/src/space.rs:464`
- Python write surface at `python/hyperon/base.py:205-221`
- `SpaceObserver` / `SpaceEvent` / `SpaceCommon` observer pattern at `hyperon-space/src/lib.rs:22-126`
- Single-process / single-threaded by intentional design (per maintainer comment at `c/src/space.rs:117-119`)
**PATCH-1** (REQUIRED for Phase 4 mirror integration): pybind11 binding for `space_register_observer` in `python/hyperonpy.cpp` is missing. Path II (Rust-only bridge service) is the Phase 4 implementation strategy; Path IV (PR upstream) is the upstream-contribution strategy.
### Python Bindings
`[PY-PARTIAL-WITH-GAPS]`
Broad coverage:
- `SpaceRef` (`base.py:168`), `add_atom`/`remove_atom`/`replace_atom` (L205-221)
- `RunnerState` (`runner.py:24`), MeTTa class (L107), run (L206), evaluate atom (L216)
- `hyperonpy.cpp:1017-1026` interpreter stepping
- `hyperonpy.cpp:1047-1053` type checking and lookup
- `hyperonpy.cpp:1070-1122` run context, MeTTa construction, module loading
**Gap**: Python observer registration is **NOT** bound (PATCH-1 above).
EventAgent (PR #852, merged commit `2fd826d4` 2025-03-14) ships at HEAD: `python/hyperon/exts/agents/agent_base.py:202-293` defines `EventAgent`, `BasicEventBus` at `events/basic_bus.py:6`. EventAgent uses a generic event bus, **NOT** bound to `SpaceEvent`/`SpaceObserver` — they are disjoint event paths in the same repo.
### C Bindings
`[C-CORE-ONLY]`
Broad runtime surface in `c/src/`:
- `space.rs:69` `space_new`; `:140-170` add/remove/replace; `:184-237` query/subst/count/iter; `:401-419` event accessors; `:464` `space_register_observer`; `:632-673` event constructors
- `metta.rs:838-882` MeTTa instance construction; `:957-969` space/tokenizer accessors; `:1005` parser-input run; `:1035` atom evaluation; `:1062-1094` module loading; `:1305-1407` runner-state stepping
C headers are **auto-generated** by cbindgen (per `c/cbindgen.toml`); there is **NO** source-controlled `c/include/` directory.
### Sandbox Modules
`python/sandbox/` is a prototype zone, **NOT** part of the packaged Python module (`python/pyproject.toml:38` packages only `hyperon`).
| Module | Verdict | Notes |
|---|---|---|
| `sql_space` | `[SANDBOX-PROTOTYPE]` | Postgres custom-Space; 130 lines; naive SQL string concat; not production |
| `mork` | `[SANDBOX-PROTOTYPE]` | TODOs at L32, L47 |
| `neurospace` | `[SANDBOX-PROTOTYPE]` | NeuralSpace, IntentSpace |
| `jetta` | `[SANDBOX-EXAMPLE-ONLY]` | Requires cloning `trueagi-io/jetta` |
| `numpy` | `[SANDBOX-PROTOTYPE]` | `numme.py` experimental |
| `pytorch` | `[SANDBOX-PROTOTYPE]` | `torchme.py` Func-Signature JSON for type-aware tensor ops |
| `bhv_binding` | unclassified | Source 1 did not enumerate |
| `repl` | unclassified | Relationship to top-level `repl/` Rust crate not characterized |
| `resolve` | unclassified | Source 1 did not enumerate |
S2-S6 must treat these as precedent and adjacency, **NOT** as packaged interfaces.
### Test Coverage
`[TEST-COVERAGE-ADEQUATE]`
Multilayer:
- Rust library tests in `lib/tests/` + inline `#[test]` blocks (52 in `interpreter.rs`, 38 in `types.rs`)
- C tests in `c/tests/`: `check_atom.c`, `check_runner.c`, `check_space.c`, `check_types.c`
- Python tests in `python/tests/`
- DAS integration tests in `integration_tests/das/`
- Test-corpus path-count: 101 files
Static audit only — tests not run during cluster-pilot extraction.
## v0.2.x Runtime Quirks Re-Verified at v0.2.10
The Magi project memory `reference_hyperon_0210_quirks.md` was originally pinned to v0.2.1 (MAGUS pin). Re-verified at HEAD `3f76dc46` (v0.2.10):
- **Q-1 — bind! + new-space**: `[QUIRK-CONFIRMED-AT-HEAD]`. `BindOp::execute` (`stdlib/module.rs:269+`) registers a token in the tokenizer. NO code path clears or garbage-collects atoms in an already-bound space. Operational guidance: do NOT treat `!(bind! &name (new-space))` as a reset of an existing live space. Use explicit `(match &name (pattern) (remove-atom &name (pattern)))` workaround.
- **Q-2 — cond**: `[QUIRK-FIXED-SINCE-V0-2-1]` (via absence). `cond` is **NOT** a builtin operator at HEAD. Use `if`, `case`, `match`, or user-defined equations. The original v0.2.1 quirk "cond is non-reducing" is no longer applicable because `cond` is not implemented.
- **Q-3 — catchall multi-reduction**: `[QUIRK-CONFIRMED-AT-HEAD]`. This is documented nondeterministic semantics, not a defect. Programs requiring deterministic dispatch must use mutually exclusive patterns; e.g., enumerate all symbols explicitly instead of using a generic variable fallback.
## Cluster-Pilot Provenance
Source 1 of the MeTTa runtime cluster pilot (closed 2026-05-08). Three-way reviewer reconciliation at:
- `scripts/archive/metta_runtime_pilot/source1_hyperon_experimental/findings_reconciled_crossmodel.txt`
Phase 4 prior art locked from AtomSpace Integration Phase 4 cluster pilot (closed 2026-05-05): Source 2 reconciliation at `scripts/archive/atomspace_integration_phase4/source2_hyperon_space_writeapi/findings_reconciled_crossmodel.txt`.
## Cross-Source Forwards (S2 — S6)
For PeTTa+metta-morph (S2), MeTTaTron (S3), MeTTaIL+FormalMeTTa (S4), MeTTaLog (S5), jetta+atomspace-metta (S6):
- Stdlib parity audits cover **both** Rust-token-registration AND MeTTa-side `stdlib.metta` definitions
- Compare against nondeterministic small-step interpreter, **NOT** deterministic rewrite assumption
- Type-system claims compared against dynamic `%Undefined%` wildcard baseline
- Module-system comparison is a major axis (active but evolving target)
- 0.2.x quirk verification baseline at HEAD `3f76dc46`
## Source Identity
- Origin:
- HEAD pinned: `3f76dc460da6961f57f69f6c3e550c59c74ada83`
- Tagged release: v0.2.10 (Merge PR #1075, 2026-02-11, Vitaly Bogdanov)
- Tag timeline: v0.2.1 (2024-10-23) → v0.2.10 (2026-02-11), 10 minor releases over ~16 months
- 7-crate Rust workspace: `hyperon-common`, `hyperon-atom`, `hyperon-space`, `hyperon-macros`, `lib`, `c`, `repl`
- Non-workspace dirs: `python/` (pybind11 bindings + sandbox), `integration_tests/das/`, `docs/`
- Tracked-file inventory: 296 files (85 .rs + 67 .metta + 65 .py + 22 .md + smaller)
- Primary maintainer: Vitaly Bogdanov (2,137 commits all-time)
## Architecture
### Interpreter Semantics
`[SMALL-STEP-INTERPRETER]` `[NONDETERMINISTIC-BRANCHING]`
Stack-based, plan/state-driven, nondeterministic. **NOT** a deterministic "first match wins" rewrite engine — multiple matches produce multiple results. Key entry points in `lib/src/metta/interpreter.rs`:
- `interpret_step` (L269) — main reduction step
- `interpret_stack` (L374) — stack dispatch with depth enforcement (L392)
- `eval_impl` (L504), `eval_result` (L559), `query` (L604)
- `chain` (L687), `collapse-bind` (L746), `unify` (L809), `superpose-bind` (L893)
- Native grounded-symbol calls (L922)
**Boundary**: programs requiring deterministic dispatch must use mutually exclusive patterns. Catchall equations (`$_`, `$other`) alongside specific equations produce multiple reductions — this is documented language semantics, not a defect.
### Type System
`[DYNAMIC-CHECKED]`
`lib/src/metta/types.rs`:
- `%Undefined%` is permissive wildcard — assigned to atoms without a user type, matches any required type (L18-19)
- `check_arg_types` (L65), `get_atom_types` (L327), `get_application_types` (L512), `UndefinedTypeMatch` (L526)
- `check_type` (L602), `validate_atom` (L637)
- Dependent-type tests at L817, L861, L1120, L1139
- Open TODOs at L42, L379, L397, L494-499, L1177, L1225, L1298
Hyperon Experimental supports expressive type checking, but should **NOT** be described as a fully-settled categorical/dependent-type verifier.
### Standard Library
`[HYBRID-RUST-PLUS-METTA-STDLIB]`
Split between Rust-side token registrations under `lib/src/metta/runner/stdlib/` and MeTTa-side definitions in `stdlib.metta` (1,421 lines). Cross-runtime audits **must** cover both layers.
Rust-side modules:
- `arithmetics.rs` (L162-198): `+`, `-`, `*`, `/`, `%`, ``, `=`, `and`, `or`, `not`, `xor`, division
- `atom.rs` (L449-474): `unique-atom`, `union-atom`, `intersection-atom`, `max-atom`, `min-atom`, `size-atom`, `index-atom`, `subtraction-atom`, `get-type`, `get-metatype`, `get-type-space`
- `core.rs` (L336-362): `pragma!`, `nop`, `sealed`, `==`, `match`, `if-equal`, `superpose`, `capture`, `_minimal-foldl-atom`
- `debug.rs` (L155-177): `trace!`, `print-alternatives!`, `=alpha`
- `math.rs` (L408-443): `pow-math`, `sqrt-math`, `abs-math`, `log-math`, etc., plus `PI` and `EXP` constants
- `module.rs` (L280-298): `import!` (L290), `include`, `mod-space!`, `print-mods!`, `bind!` (L269), `module-space-no-deps`
- `package.rs` (L113-117): `register-module!`, `git-module!`
- `space.rs` (L206-223): `new-space`, `get-state`, `change-state!`, `get-atoms`, `add-atom`, `remove-atom`
MeTTa-side definitions in `stdlib.metta`: `return` (L47), `function` (L54), `eval` (L61), `chain` (L78), `unify` (L88), `cons-atom` (L96), `decons-atom` (L103), `collapse-bind` (L239), `superpose-bind` (L246), `metta` (L255), `switch` (L345-362), `if` (L511-513), `let`/`let*` (L542-553), `collapse` (L1203), `case` (L1224-1233).
**NOTE**: there is **NO** `replace-atom!` MeTTa op at HEAD. PATCH-2 from the AtomSpace Integration Phase 4 cluster pilot recommends adding it.
### Built-in Modules
`[BUILTIN-FULLY-WIRED]`
`lib/src/metta/runner/builtin_mods/mod.rs` registers six loaders:
- `random`, `skel`, `fileio`, `json`
- `catalog` (`pkg_mgmt` Cargo feature)
- `das` (`das` Cargo feature, default-enabled per `lib/Cargo.toml:46`)
Each module pairs a `.rs` registration file with a `.metta` doc file (`catalog.metta`, `das.metta`, `fileio.metta`, `json.metta`, `random.metta`, `skel.metta`).
DAS is available as a default feature and builtin module surface, but does **NOT** mean a running distributed DAS service is embedded in the local runtime — `metta-bus-client` connects to a remote DAS service.
### Module System
`[MODULE-SYSTEM-PARTIAL]`
Implemented and active but evolving (per `docs/modules_internal_discussion.md`'s "poor man's" public/private scope concept).
`lib/src/metta/runner/modules/mod.rs`:
- `ModId` (L27), `MettaMod` (L56), resource and loader fields (L58, L62)
- `import_dependency_as` (L107), `import_item_from_dependency_as` (L131), `import_all_from_dependency` (L181)
- Accessors path/name/package/space/tokenizer/resource (L251-278)
- Descriptor state (L314), module init (L439), `ModuleLoader` trait (L563), `Resource` (L608)
- Name resolution at `mod_names.rs:265` and `:276`
Imports via `import!` (registered at `stdlib/module.rs:290`) create separate `DynSpace` instances.
### AtomIndex / AtomTrie
`[IN-MEMORY-ATOMTRIE-INDEX]` `[NO-BENCHMARK-CLAIMS]`
`hyperon-space/src/index/`:
- `AtomIndex` (`mod.rs:159`), insert (`:177`), query (`:192`), remove (`:207`)
- `AtomTrie` (`trie.rs:201`, 930 lines), insert (`:232`), query (`:261`), remove (`:395`)
Concentrated implementation period 2025-01-31 → 2025-02-11 (initial implementation, GroundingSpace integration, duplication strategy parameter, AtomStorage/AtomTrieNode separation, compactness improvements). Size-prefix optimization landed at `120c2279` (2025-08-26) — *"Prefix expressions with size in atomspace index to recognize them faster"*.
**NO** quantitative scaling ceilings claimed at this time. Existing benches at `hyperon-space/benches/atom_index.rs` and `lib/benches/grounding_space.rs` operate at 100/x10/x100 atom scales only. An empirical bench harness is required for any production scaling claims.
### Hyperon Space Write API and Observer Pattern
(Phase 4 prior art — re-confirmed at HEAD)
The Hyperon Space write surface is complete at the Space/C/Python layers:
- `SpaceMut::add` / `remove` / `replace` at `hyperon-space/src/lib.rs:237/255/275`
- `GroundingSpace ` concrete impl at `lib/src/space/grounding/mod.rs:14-21`; inherent `add`/`remove`/`replace` at `:70/:92/:119`
- C-API write surface at `c/src/space.rs:140-143`; observer registration at `c/src/space.rs:464`
- Python write surface at `python/hyperon/base.py:205-221`
- `SpaceObserver` / `SpaceEvent` / `SpaceCommon` observer pattern at `hyperon-space/src/lib.rs:22-126`
- Single-process / single-threaded by intentional design (per maintainer comment at `c/src/space.rs:117-119`)
**PATCH-1** (REQUIRED for Phase 4 mirror integration): pybind11 binding for `space_register_observer` in `python/hyperonpy.cpp` is missing. Path II (Rust-only bridge service) is the Phase 4 implementation strategy; Path IV (PR upstream) is the upstream-contribution strategy.
### Python Bindings
`[PY-PARTIAL-WITH-GAPS]`
Broad coverage:
- `SpaceRef` (`base.py:168`), `add_atom`/`remove_atom`/`replace_atom` (L205-221)
- `RunnerState` (`runner.py:24`), MeTTa class (L107), run (L206), evaluate atom (L216)
- `hyperonpy.cpp:1017-1026` interpreter stepping
- `hyperonpy.cpp:1047-1053` type checking and lookup
- `hyperonpy.cpp:1070-1122` run context, MeTTa construction, module loading
**Gap**: Python observer registration is **NOT** bound (PATCH-1 above).
EventAgent (PR #852, merged commit `2fd826d4` 2025-03-14) ships at HEAD: `python/hyperon/exts/agents/agent_base.py:202-293` defines `EventAgent`, `BasicEventBus` at `events/basic_bus.py:6`. EventAgent uses a generic event bus, **NOT** bound to `SpaceEvent`/`SpaceObserver` — they are disjoint event paths in the same repo.
### C Bindings
`[C-CORE-ONLY]`
Broad runtime surface in `c/src/`:
- `space.rs:69` `space_new`; `:140-170` add/remove/replace; `:184-237` query/subst/count/iter; `:401-419` event accessors; `:464` `space_register_observer`; `:632-673` event constructors
- `metta.rs:838-882` MeTTa instance construction; `:957-969` space/tokenizer accessors; `:1005` parser-input run; `:1035` atom evaluation; `:1062-1094` module loading; `:1305-1407` runner-state stepping
C headers are **auto-generated** by cbindgen (per `c/cbindgen.toml`); there is **NO** source-controlled `c/include/` directory.
### Sandbox Modules
`python/sandbox/` is a prototype zone, **NOT** part of the packaged Python module (`python/pyproject.toml:38` packages only `hyperon`).
| Module | Verdict | Notes |
|---|---|---|
| `sql_space` | `[SANDBOX-PROTOTYPE]` | Postgres custom-Space; 130 lines; naive SQL string concat; not production |
| `mork` | `[SANDBOX-PROTOTYPE]` | TODOs at L32, L47 |
| `neurospace` | `[SANDBOX-PROTOTYPE]` | NeuralSpace, IntentSpace |
| `jetta` | `[SANDBOX-EXAMPLE-ONLY]` | Requires cloning `trueagi-io/jetta` |
| `numpy` | `[SANDBOX-PROTOTYPE]` | `numme.py` experimental |
| `pytorch` | `[SANDBOX-PROTOTYPE]` | `torchme.py` Func-Signature JSON for type-aware tensor ops |
| `bhv_binding` | unclassified | Source 1 did not enumerate |
| `repl` | unclassified | Relationship to top-level `repl/` Rust crate not characterized |
| `resolve` | unclassified | Source 1 did not enumerate |
S2-S6 must treat these as precedent and adjacency, **NOT** as packaged interfaces.
### Test Coverage
`[TEST-COVERAGE-ADEQUATE]`
Multilayer:
- Rust library tests in `lib/tests/` + inline `#[test]` blocks (52 in `interpreter.rs`, 38 in `types.rs`)
- C tests in `c/tests/`: `check_atom.c`, `check_runner.c`, `check_space.c`, `check_types.c`
- Python tests in `python/tests/`
- DAS integration tests in `integration_tests/das/`
- Test-corpus path-count: 101 files
Static audit only — tests not run during cluster-pilot extraction.
## v0.2.x Runtime Quirks Re-Verified at v0.2.10
The Magi project memory `reference_hyperon_0210_quirks.md` was originally pinned to v0.2.1 (MAGUS pin). Re-verified at HEAD `3f76dc46` (v0.2.10):
- **Q-1 — bind! + new-space**: `[QUIRK-CONFIRMED-AT-HEAD]`. `BindOp::execute` (`stdlib/module.rs:269+`) registers a token in the tokenizer. NO code path clears or garbage-collects atoms in an already-bound space. Operational guidance: do NOT treat `!(bind! &name (new-space))` as a reset of an existing live space. Use explicit `(match &name (pattern) (remove-atom &name (pattern)))` workaround.
- **Q-2 — cond**: `[QUIRK-FIXED-SINCE-V0-2-1]` (via absence). `cond` is **NOT** a builtin operator at HEAD. Use `if`, `case`, `match`, or user-defined equations. The original v0.2.1 quirk "cond is non-reducing" is no longer applicable because `cond` is not implemented.
- **Q-3 — catchall multi-reduction**: `[QUIRK-CONFIRMED-AT-HEAD]`. This is documented nondeterministic semantics, not a defect. Programs requiring deterministic dispatch must use mutually exclusive patterns; e.g., enumerate all symbols explicitly instead of using a generic variable fallback.
## Cluster-Pilot Provenance
Source 1 of the MeTTa runtime cluster pilot (closed 2026-05-08). Three-way reviewer reconciliation at:
- `scripts/archive/metta_runtime_pilot/source1_hyperon_experimental/findings_reconciled_crossmodel.txt`
Phase 4 prior art locked from AtomSpace Integration Phase 4 cluster pilot (closed 2026-05-05): Source 2 reconciliation at `scripts/archive/atomspace_integration_phase4/source2_hyperon_space_writeapi/findings_reconciled_crossmodel.txt`.
## Cross-Source Forwards (S2 — S6)
For PeTTa+metta-morph (S2), MeTTaTron (S3), MeTTaIL+FormalMeTTa (S4), MeTTaLog (S5), jetta+atomspace-metta (S6):
- Stdlib parity audits cover **both** Rust-token-registration AND MeTTa-side `stdlib.metta` definitions
- Compare against nondeterministic small-step interpreter, **NOT** deterministic rewrite assumption
- Type-system claims compared against dynamic `%Undefined%` wildcard baseline
- Module-system comparison is a major axis (active but evolving target)
- 0.2.x quirk verification baseline at HEAD `3f76dc46`