diff --git a/core/cli.py b/core/cli.py
index 1587b47d..ddca48e0 100644
--- a/core/cli.py
+++ b/core/cli.py
@@ -23,9 +23,18 @@ _CORE_RS_DIR = _REPO_ROOT / "core-rs"
 _CORE_RS_MANIFEST = _CORE_RS_DIR / "Cargo.toml"
 
 DESCRIPTION = "CORE versor engine command suite."
-EPILOG = "Examples:\n  core chat\n  core trace \"word beginning truth\"\n  core trace --output-language grc --frame-pack grc --json \"logos\"\n  core rust status\n  core rust build\n  core oov covenant\n  core pack list\n  core pack verify en_minimal_v1\n  core test --suite smoke -q\n  core test --suite cognition -q\n  core test -- tests/test_alignment_graph.py -q\n  core eval cognition\n  core eval cognition --json"
+EPILOG = "Examples:\n  core chat\n  core trace \"word beginning truth\"\n  core trace --output-language grc --frame-pack grc --json \"logos\"\n  core rust status\n  core rust build\n  core oov covenant\n  core pack list\n  core pack verify en_minimal_v1\n  core test --suite fast -q\n  core test --suite smoke -q\n  core test --suite cognition -q\n  core test -- tests/test_alignment_graph.py -q\n  core eval cognition\n  core eval cognition --json"
 
 _TEST_SUITES: dict[str, tuple[str, ...]] = {
+    "fast": (
+        "tests/test_cli_test_suites.py",
+        "tests/test_runtime_config.py",
+        "tests/test_core_semantic_seed_pack.py",
+        "tests/test_intent_proposition_graph.py",
+        "tests/test_articulation_realizer_v2.py",
+        "tests/test_reviewed_teaching_loop.py",
+        "tests/test_cognitive_eval_harness.py",
+    ),
     "smoke": (
         "tests/test_chat_runtime.py",
         "tests/test_achat.py",
diff --git a/language_packs/compiler.py b/language_packs/compiler.py
index 72133c40..8f680007 100644
--- a/language_packs/compiler.py
+++ b/language_packs/compiler.py
@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import hashlib
 import json
+from functools import lru_cache
 from pathlib import Path
 from typing import TYPE_CHECKING
 
@@ -330,6 +331,22 @@ def _parse_entry(payload: dict) -> LexicalEntry:
     )
 
 
+def _clone_manifold(source: VocabManifold) -> VocabManifold:
+    """Return a mutable defensive copy of a cached compiled manifold."""
+    clone = VocabManifold()
+    for idx in range(len(source)):
+        surface = source.get_word_at(idx)
+        clone.add(
+            surface,
+            source.get_versor_at(idx),
+            morphology=source.morphology_for_word(surface),
+            language=source.language_for_word(surface),
+            energy=source.energy_for_word(surface),
+            valence=source.valence_for_word(surface),
+        )
+    return clone
+
+
 def _apply_alignment_corrections(home_manifold: VocabManifold, home_id_map: dict[str, str], foreign_manifold: VocabManifold, foreign_id_map: dict[str, str], pack_id: str) -> None:
     from alignment.graph import load_alignment
 
@@ -351,7 +368,8 @@ def _apply_alignment_corrections(home_manifold: VocabManifold, home_id_map: dict
         home_manifold.update(source_surface, corrected)
 
 
-def load_pack(pack_id: str) -> tuple[LanguagePackManifest, VocabManifold]:
+@lru_cache(maxsize=None)
+def _load_pack_cached(pack_id: str) -> tuple[LanguagePackManifest, VocabManifold]:
     pack_dir = Path(__file__).parent / "data" / pack_id
     manifest_path = pack_dir / "manifest.json"
     lexicon_path = pack_dir / "lexicon.jsonl"
@@ -403,13 +421,14 @@ def load_pack(pack_id: str) -> tuple[LanguagePackManifest, VocabManifold]:
     return manifest, home_manifold
 
 
-def load_mounted_packs(pack_ids: tuple[str, ...] | list[str]) -> VocabManifold:
-    """
-    Mount multiple compiled packs into one exact-search manifold.
+def load_pack(pack_id: str) -> tuple[LanguagePackManifest, VocabManifold]:
+    manifest, manifold = _load_pack_cached(pack_id)
+    return manifest, _clone_manifold(manifold)
 
-    The mounted field is a union of already-compiled Cl(4,1) points. It does
-    not add a side index, fallback embedding, or approximate distance path.
-    """
+
+@lru_cache(maxsize=None)
+def _load_mounted_packs_cached(pack_ids: tuple[str, ...]) -> VocabManifold:
+    """Compile a mounted pack union once; callers receive defensive copies."""
     mounted = VocabManifold()
     seen: set[str] = set()
     primary_groups: dict[str, list[tuple[str, str]]] = {}
@@ -439,6 +458,16 @@ def load_mounted_packs(pack_ids: tuple[str, ...] | list[str]) -> VocabManifold:
     return mounted
 
 
+def load_mounted_packs(pack_ids: tuple[str, ...] | list[str]) -> VocabManifold:
+    """
+    Mount multiple compiled packs into one exact-search manifold.
+
+    The mounted field is a union of already-compiled Cl(4,1) points. It does
+    not add a side index, fallback embedding, or approximate distance path.
+    """
+    return _clone_manifold(_load_mounted_packs_cached(tuple(pack_ids)))
+
+
 def _apply_mounted_primary_domain_resonance(
     mounted: VocabManifold,
     primary_groups: dict[str, list[tuple[str, str]]],
@@ -474,7 +503,8 @@ def _infer_foreign_pack_ids(home_pack_id: str, graph: "AlignmentGraph") -> list[
     return sorted(foreign)
 
 
-def load_pack_entries(pack_id: str) -> list[LexicalEntry]:
+@lru_cache(maxsize=None)
+def _load_pack_entries_cached(pack_id: str) -> tuple[LexicalEntry, ...]:
     pack_dir = Path(__file__).parent / "data" / pack_id
     lexicon_path = pack_dir / "lexicon.jsonl"
     entries: list[LexicalEntry] = []
@@ -482,7 +512,11 @@ def load_pack_entries(pack_id: str) -> list[LexicalEntry]:
         if line.strip():
             entries.append(_parse_entry(json.loads(line)))
     _validate_morphology_links(pack_id, entries)
-    return entries
+    return tuple(entries)
+
+
+def load_pack_entries(pack_id: str) -> list[LexicalEntry]:
+    return list(_load_pack_entries_cached(pack_id))
 
 
 def _validate_morphology_links(pack_id: str, entries: list[LexicalEntry]) -> None:
diff --git a/tests/test_cli_test_suites.py b/tests/test_cli_test_suites.py
index e7467245..c22be2df 100644
--- a/tests/test_cli_test_suites.py
+++ b/tests/test_cli_test_suites.py
@@ -12,6 +12,7 @@ def test_core_test_lists_curated_suites(capsys) -> None:
 
     captured = capsys.readouterr()
     assert rc == 0
+    assert "fast" in captured.out.splitlines()
     assert "smoke" in captured.out.splitlines()
     assert "cognition" in captured.out.splitlines()
     assert "teaching" in captured.out.splitlines()
@@ -40,6 +41,26 @@ def test_core_test_suite_expands_to_expected_pytest_paths(monkeypatch) -> None:
     assert "-q" in command
 
 
+def test_core_test_fast_suite_expands_to_iteration_lane(monkeypatch) -> None:
+    calls: list[tuple[str, ...]] = []
+
+    def fake_run(*args: str, check: bool = False, cwd=None) -> int:
+        calls.append(args)
+        return 0
+
+    monkeypatch.setattr(cli, "_run", fake_run)
+
+    rc = cli.main(["test", "--suite", "fast", "-q"])
+
+    assert rc == 0
+    command = calls[0]
+    assert "tests/test_cli_test_suites.py" in command
+    assert "tests/test_runtime_config.py" in command
+    assert "tests/test_core_semantic_seed_pack.py" in command
+    assert "tests/test_cognitive_eval_harness.py" in command
+    assert "tests/" not in command
+
+
 def test_core_test_suite_accepts_pytest_flags_without_separator(monkeypatch) -> None:
     calls: list[tuple[str, ...]] = []
 
diff --git a/tests/test_language_pack_cache.py b/tests/test_language_pack_cache.py
new file mode 100644
index 00000000..16ff67d3
--- /dev/null
+++ b/tests/test_language_pack_cache.py
@@ -0,0 +1,40 @@
+"""Language-pack cache isolation tests."""
+
+from __future__ import annotations
+
+from language_packs.compiler import load_mounted_packs, load_pack, load_pack_entries
+
+
+def test_load_pack_returns_defensive_manifold_copies() -> None:
+    _manifest_a, manifold_a = load_pack("en_core_cognition_v1")
+    _manifest_b, manifold_b = load_pack("en_core_cognition_v1")
+
+    original_len = len(manifold_b)
+    manifold_a.insert_transient("cache_probe_token", manifold_a.get_versor("truth"))
+
+    assert len(manifold_a) == original_len + 1
+    assert len(manifold_b) == original_len
+    assert not manifold_b.is_transient("cache_probe_token")
+
+
+def test_load_mounted_packs_returns_defensive_manifold_copies() -> None:
+    packs = ("en_minimal_v1", "en_core_cognition_v1")
+    mounted_a = load_mounted_packs(packs)
+    mounted_b = load_mounted_packs(packs)
+
+    original_len = len(mounted_b)
+    mounted_a.insert_transient("mounted_cache_probe_token", mounted_a.get_versor("truth"))
+
+    assert len(mounted_a) == original_len + 1
+    assert len(mounted_b) == original_len
+    assert not mounted_b.is_transient("mounted_cache_probe_token")
+
+
+def test_load_pack_entries_returns_new_list_from_cached_tuple() -> None:
+    entries_a = load_pack_entries("en_core_cognition_v1")
+    entries_b = load_pack_entries("en_core_cognition_v1")
+
+    entries_a.pop()
+
+    assert len(entries_a) == len(entries_b) - 1
+    assert entries_b[-1].entry_id == "en-core-cog-055"