diff --git a/docs/DescriptionAndMilestones.md b/docs/DescriptionAndMilestones.md
index 9c80e21..a0811de 100644
--- a/docs/DescriptionAndMilestones.md
+++ b/docs/DescriptionAndMilestones.md
@@ -93,7 +93,7 @@ Long-term memory remains a host persistence responsibility, not an engine-owned
 
 ### 0.6.x
 
-The 0.6.x line completed checkpoint support, precompiler boundary hardening, and
+The 0.6.x line completed checkpoint support, preprocessor boundary hardening, and
 regression/conformance surfaces that prepare the project for the next milestone.
 
 ### 0.7 — Auditability & Boundary Hardening
@@ -119,7 +119,7 @@ Make engine behavior inspectable and externally controllable without guessing.
   - requires `--with-precompiler`
   - never implicit
   - inspectable via preview / JSON output
-- Explicit precompiler policy for multi-line, multi-sentence, and conversational-prefix input
+- Explicit preprocessor policy for multi-line, multi-sentence, and conversational-prefix input
   (for example `ok. prohibit peanuts`, `sure - use docker`, mixed conversational + directive content)
   that is rule-based, fixture-covered, and inspectable
 - Define policy for directive-adjacent mixed-intent payloads
@@ -131,7 +131,7 @@ Make engine behavior inspectable and externally controllable without guessing.
 - No expansion of authoritative state model
 - No implicit behavior
 - No heuristic-heavy parsing
-- Preserve separation between engine, precompiler, and host/controller layers
+- Preserve separation between engine, preprocessor, and host/controller layers
 
 ### Post-0.7 Direction
 
@@ -145,7 +145,7 @@ Conceptual completion is a stable minimal contract, not feature accumulation.
 
 - Stable minimal engine contract
 - Deterministic and inspectable behavior
-- Strict compiler / precompiler / host separation
+- Strict compiler / preprocessor / host separation
 - No implicit behavior
 - No authoritative state-model expansion
 - Cross-language consistency with Python as source of truth
diff --git a/examples/integrations/litellm/with_preprocessor.py b/examples/integrations/litellm/with_preprocessor.py
index 18d2f62..b250a37 100644
--- a/examples/integrations/litellm/with_preprocessor.py
+++ b/examples/integrations/litellm/with_preprocessor.py
@@ -28,7 +28,7 @@
 from context_compiler.engine import Engine
 from experimental.preprocessor import (
     PRECOMPILE_OUTCOME_DIRECTIVE,
-    parse_precompiler_output,
+    parse_preprocessor_output,
     precompile_heuristic,
     render_prompt,
 )
@@ -236,7 +236,7 @@ def _llm_fallback_precompile(message: str, state: State) -> str | None:
     except Exception:
         return None
 
-    parsed = parse_precompiler_output(raw_output, source_input=message)
+    parsed = parse_preprocessor_output(raw_output, source_input=message)
     if parsed is None:
         return None
     return parsed
@@ -251,7 +251,7 @@ def _precompile_user_input(message: str, state: State) -> str | None:
             heuristic_result["outcome"] == PRECOMPILE_OUTCOME_DIRECTIVE
             and heuristic_result["directive"]
         ):
-            parsed = parse_precompiler_output(heuristic_result["directive"])
+            parsed = parse_preprocessor_output(heuristic_result["directive"])
             logger.debug("preprocessor: heuristic_directive=%r", heuristic_result["directive"])
             if parsed is not None:
                 return parsed
diff --git a/examples/integrations/litellm_proxy/context_compiler_precall_hook_with_preprocessor.py b/examples/integrations/litellm_proxy/context_compiler_precall_hook_with_preprocessor.py
index 5f358f5..27acbcc 100644
--- a/examples/integrations/litellm_proxy/context_compiler_precall_hook_with_preprocessor.py
+++ b/examples/integrations/litellm_proxy/context_compiler_precall_hook_with_preprocessor.py
@@ -34,7 +34,7 @@ class CustomLogger:  # type: ignore[no-redef]
 )
 from experimental.preprocessor import (
     PRECOMPILE_OUTCOME_DIRECTIVE,
-    parse_precompiler_output,
+    parse_preprocessor_output,
     precompile_heuristic,
     render_prompt,
 )
@@ -180,7 +180,7 @@ def _llm_fallback_precompile(message: str, state: State) -> str | None:
     except Exception:
         return None
 
-    parsed = parse_precompiler_output(raw_output, source_input=message)
+    parsed = parse_preprocessor_output(raw_output, source_input=message)
     if parsed is None:
         return None
     return parsed
@@ -203,7 +203,7 @@ def _precompile_last_user_message(message: str, state: State | None) -> str | No
             heuristic_result["outcome"] == PRECOMPILE_OUTCOME_DIRECTIVE
             and heuristic_result["directive"]
         ):
-            parsed = parse_precompiler_output(heuristic_result["directive"])
+            parsed = parse_preprocessor_output(heuristic_result["directive"])
             if parsed is not None:
                 return parsed
     except Exception:
diff --git a/examples/integrations/openwebui/open_webui_pipe_with_preprocessor.py b/examples/integrations/openwebui/open_webui_pipe_with_preprocessor.py
index 116ffa4..d943a28 100644
--- a/examples/integrations/openwebui/open_webui_pipe_with_preprocessor.py
+++ b/examples/integrations/openwebui/open_webui_pipe_with_preprocessor.py
@@ -51,7 +51,7 @@ def Field(*, default: Any, description: str = "") -> Any:  # type: ignore[no-red
 from context_compiler.engine import Engine
 from experimental.preprocessor import (
     PRECOMPILE_OUTCOME_DIRECTIVE,
-    parse_precompiler_output,
+    parse_preprocessor_output,
     precompile_heuristic,
     render_prompt,
 )
@@ -671,7 +671,7 @@ async def _llm_fallback_precompile(
             return None, normalized_error
 
         raw_output = _extract_completion_content(response)
-        parsed = parse_precompiler_output(raw_output, source_input=message)
+        parsed = parse_preprocessor_output(raw_output, source_input=message)
         if parsed is None:
             return None, None
         return parsed, None
@@ -694,7 +694,7 @@ async def _precompile_user_input(
             heuristic_result["outcome"] == PRECOMPILE_OUTCOME_DIRECTIVE
             and heuristic_result["directive"]
         ):
-            parsed = parse_precompiler_output(heuristic_result["directive"])
+            parsed = parse_preprocessor_output(heuristic_result["directive"])
             if parsed is not None:
                 return parsed, None
 
diff --git a/experimental/preprocessor/README.md b/experimental/preprocessor/README.md
index e079f48..d46de13 100644
--- a/experimental/preprocessor/README.md
+++ b/experimental/preprocessor/README.md
@@ -11,6 +11,11 @@ Recommended install for integrations using this package:
 Integrations should import this package from the installed environment rather
 than using repo-relative preprocessor paths.
 
+Compatibility note:
+- Prefer `heuristic_preprocessor.py` and `parse_preprocessor_output(...)`.
+- `heuristic_precompiler.py` and `parse_precompiler_output(...)` remain
+  supported compatibility aliases in 0.6.x.
+
 ## Modules
 
 - `heuristic_preprocessor.py`: conservative structural preprocessing pass.
diff --git a/experimental/preprocessor/output_validation.py b/experimental/preprocessor/output_validation.py
index 088fee6..b0bb646 100644
--- a/experimental/preprocessor/output_validation.py
+++ b/experimental/preprocessor/output_validation.py
@@ -1,9 +1,9 @@
 """Shared preprocessor output normalization and validation helpers.
 
 Public API:
-- validate_precompiler_output
-- parse_precompiler_output
 - parse_preprocessor_output
+- parse_precompiler_output (compatibility alias)
+- validate_precompiler_output
 
 Internal helpers are implementation details and may change.
 """
@@ -146,7 +146,7 @@ def _validate_text_output(raw_output: str) -> PrecompilerValidationResult:
 def validate_precompiler_output(
     raw_output: object, *, source_input: str | None = None
 ) -> PrecompilerValidationResult:
-    """Validate raw precompiler output into a strict classification/output result.
+    """Validate raw preprocessor output into a strict classification/output result.
 
     Contract:
         - directive: output is a canonical directive string
diff --git a/pyproject.toml b/pyproject.toml
index d2c65f6..2bed5ba 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "context-compiler"
-version = "0.6.15"
+version = "0.6.16"
 description = "Deterministic conversational state engine for LLM applications."
 readme = "README.md"
 requires-python = ">=3.11"
diff --git a/src/context_compiler/repl.py b/src/context_compiler/repl.py
index 78f1e88..fc7eab7 100644
--- a/src/context_compiler/repl.py
+++ b/src/context_compiler/repl.py
@@ -1,7 +1,7 @@
 import sys
 from typing import TextIO
 
-from experimental.preprocessor.output_validation import parse_precompiler_output
+from experimental.preprocessor.output_validation import parse_preprocessor_output
 
 from . import __version__, create_engine, get_policy_items, get_premise_value
 from .engine import Decision, DecisionKind, Engine, State
@@ -107,7 +107,7 @@ def _compile_input(raw_input: str, engine: Engine, *, use_precompiler: bool) ->
         return raw_input
     if _has_pending_clarification(engine):
         return raw_input
-    parsed = parse_precompiler_output(raw_input, source_input=raw_input)
+    parsed = parse_preprocessor_output(raw_input, source_input=raw_input)
     return parsed if parsed is not None else raw_input
 
 
diff --git a/tests/fixtures/README.md b/tests/fixtures/README.md
index 4cbfb42..96e5261 100644
--- a/tests/fixtures/README.md
+++ b/tests/fixtures/README.md
@@ -1,16 +1,19 @@
-# Conformance Fixtures
+# Fixture Suites
 
-These fixtures define the cross-language conformance contract for the Context Compiler.
+This directory contains multiple fixture suites with different contracts.
 
-## Layout
+## Fixture types
 
-[`conformance/`](conformance/)
+* [`conformance/`](conformance/) — core engine cross-language conformance contract.
+* [`engine-regression/structured/`](engine-regression/structured/) — deterministic per-turn engine regression fixtures (including checkpoint snapshots).
+* [`preprocessor/`](preprocessor/) — preprocessor heuristic and validation fixtures.
 
-* [`step/`](conformance/step/)
-* [`transcript/`](conformance/transcript/)
+`conformance/` and `engine-regression/structured/` both cover engine behavior at different layers; preprocessor fixtures are intentionally separate from the core engine conformance contract.
 
 ## Step fixtures
 
+For [`conformance/step/`](conformance/step/):
+
 Each step fixture runs:
 
 1. optional `prelude` (array of prior user inputs)
@@ -27,6 +30,8 @@ Then asserts:
 
 ## Transcript fixtures
 
+For [`conformance/transcript/`](conformance/transcript/):
+
 Replay messages using `compile_transcript(messages)`.
 
 Results are normalized to:
@@ -36,6 +41,8 @@ Results are normalized to:
 
 ## Prompt matching
 
+For conformance transcript fixtures:
+
 * If `prompt_to_user` is a string → exact match
 * If `prompt_to_user` is `null` → any non-empty string is accepted
 
@@ -43,6 +50,35 @@ Results are normalized to:
 
 Fixtures reflect current Python behavior and tests.
 
+## Engine regression fixtures
+
+[`engine-regression/structured/`](engine-regression/structured/)
+
+These fixtures capture deterministic per-turn engine behavior, including checkpoint snapshots, and are exercised by [`tests/test_structured_regression.py`](../test_structured_regression.py).
+
+They validate:
+
+* per-turn input handling
+* `Decision.kind` outcomes
+* clarification prompt behavior
+* checkpoint export parity against expected snapshots
+* continuation state restoration from checkpoints
+
+## Preprocessor fixtures
+
+[`preprocessor/`](preprocessor/)
+
+These fixtures cover preprocessor behavior (heuristic classification plus output validation), separate from the core engine conformance contract above.
+
+They are exercised by [`tests/test_preprocessor_conformance.py`](../test_preprocessor_conformance.py), including deterministic replay and validation-boundary checks (only validated directive output may pass through).
+
+They validate:
+
+* heuristic classification determinism
+* directive extraction and normalization
+* output validation boundaries
+* reject/unknown safety handling for ambiguous and near-miss inputs
+
 ## Test runner
 
 See [`tests/test_fixtures.py`](../test_fixtures.py) for execution details.
diff --git a/tests/fixtures/engine-regression/structured/README.md b/tests/fixtures/engine-regression/structured/README.md
index 853b3f5..800e5e7 100644
--- a/tests/fixtures/engine-regression/structured/README.md
+++ b/tests/fixtures/engine-regression/structured/README.md
@@ -48,12 +48,12 @@ They do **not** cover:
 
 - REPL / user-facing formatting
 - LLM integration behavior
-- precompiler / heuristic directive generation
+- preprocessor / heuristic directive generation
 
 These surfaces are tested separately because:
 
 - REPL output may intentionally differ from the underlying state representation
-- precompiler behavior is non-deterministic and outside the engine contract
+- preprocessor behavior is non-deterministic and outside the engine contract
 
 This fixture set is the **canonical engine-level conformance surface**, and may be reused by other implementations (e.g., TypeScript) to validate identical engine behavior.
 
diff --git a/tests/fixtures/precompiler/admin-alias-remove-policies-unknown.json b/tests/fixtures/preprocessor/admin-alias-remove-policies-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/admin-alias-remove-policies-unknown.json
rename to tests/fixtures/preprocessor/admin-alias-remove-policies-unknown.json
diff --git a/tests/fixtures/precompiler/admin-alias-reset-policy-unknown.json b/tests/fixtures/preprocessor/admin-alias-reset-policy-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/admin-alias-reset-policy-unknown.json
rename to tests/fixtures/preprocessor/admin-alias-reset-policy-unknown.json
diff --git a/tests/fixtures/precompiler/ambiguous-directive-adjacent.json b/tests/fixtures/preprocessor/ambiguous-directive-adjacent.json
similarity index 100%
rename from tests/fixtures/precompiler/ambiguous-directive-adjacent.json
rename to tests/fixtures/preprocessor/ambiguous-directive-adjacent.json
diff --git a/tests/fixtures/precompiler/canonical-directive-clear-state.json b/tests/fixtures/preprocessor/canonical-directive-clear-state.json
similarity index 100%
rename from tests/fixtures/precompiler/canonical-directive-clear-state.json
rename to tests/fixtures/preprocessor/canonical-directive-clear-state.json
diff --git a/tests/fixtures/precompiler/canonical-directive-prohibit-peanuts.json b/tests/fixtures/preprocessor/canonical-directive-prohibit-peanuts.json
similarity index 100%
rename from tests/fixtures/precompiler/canonical-directive-prohibit-peanuts.json
rename to tests/fixtures/preprocessor/canonical-directive-prohibit-peanuts.json
diff --git a/tests/fixtures/precompiler/malformed-replacement-instead-docker-unknown.json b/tests/fixtures/preprocessor/malformed-replacement-instead-docker-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/malformed-replacement-instead-docker-unknown.json
rename to tests/fixtures/preprocessor/malformed-replacement-instead-docker-unknown.json
diff --git a/tests/fixtures/precompiler/mixed-intent-unknown.json b/tests/fixtures/preprocessor/mixed-intent-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/mixed-intent-unknown.json
rename to tests/fixtures/preprocessor/mixed-intent-unknown.json
diff --git a/tests/fixtures/precompiler/modal-please-clear-state-unknown.json b/tests/fixtures/preprocessor/modal-please-clear-state-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/modal-please-clear-state-unknown.json
rename to tests/fixtures/preprocessor/modal-please-clear-state-unknown.json
diff --git a/tests/fixtures/precompiler/natural-language-dont-use-unknown.json b/tests/fixtures/preprocessor/natural-language-dont-use-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/natural-language-dont-use-unknown.json
rename to tests/fixtures/preprocessor/natural-language-dont-use-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-change-premise-missing-to-unknown.json b/tests/fixtures/preprocessor/near-miss-change-premise-missing-to-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-change-premise-missing-to-unknown.json
rename to tests/fixtures/preprocessor/near-miss-change-premise-missing-to-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-change-premise-to-empty-unknown.json b/tests/fixtures/preprocessor/near-miss-change-premise-to-empty-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-change-premise-to-empty-unknown.json
rename to tests/fixtures/preprocessor/near-miss-change-premise-to-empty-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-prohibit-empty-unknown.json b/tests/fixtures/preprocessor/near-miss-prohibit-empty-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-prohibit-empty-unknown.json
rename to tests/fixtures/preprocessor/near-miss-prohibit-empty-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-remove-policy-empty-unknown.json b/tests/fixtures/preprocessor/near-miss-remove-policy-empty-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-remove-policy-empty-unknown.json
rename to tests/fixtures/preprocessor/near-miss-remove-policy-empty-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-set-premise-empty-unknown.json b/tests/fixtures/preprocessor/near-miss-set-premise-empty-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-set-premise-empty-unknown.json
rename to tests/fixtures/preprocessor/near-miss-set-premise-empty-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-set-premise-to-unknown.json b/tests/fixtures/preprocessor/near-miss-set-premise-to-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-set-premise-to-unknown.json
rename to tests/fixtures/preprocessor/near-miss-set-premise-to-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-use-empty-unknown.json b/tests/fixtures/preprocessor/near-miss-use-empty-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-use-empty-unknown.json
rename to tests/fixtures/preprocessor/near-miss-use-empty-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-use-instead-of-missing-new-item-unknown.json b/tests/fixtures/preprocessor/near-miss-use-instead-of-missing-new-item-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-use-instead-of-missing-new-item-unknown.json
rename to tests/fixtures/preprocessor/near-miss-use-instead-of-missing-new-item-unknown.json
diff --git a/tests/fixtures/precompiler/near-miss-use-instead-of-missing-old-item-unknown.json b/tests/fixtures/preprocessor/near-miss-use-instead-of-missing-old-item-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/near-miss-use-instead-of-missing-old-item-unknown.json
rename to tests/fixtures/preprocessor/near-miss-use-instead-of-missing-old-item-unknown.json
diff --git a/tests/fixtures/precompiler/ordinary-non-directive.json b/tests/fixtures/preprocessor/ordinary-non-directive.json
similarity index 100%
rename from tests/fixtures/precompiler/ordinary-non-directive.json
rename to tests/fixtures/preprocessor/ordinary-non-directive.json
diff --git a/tests/fixtures/precompiler/question-use-docker-unknown.json b/tests/fixtures/preprocessor/question-use-docker-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/question-use-docker-unknown.json
rename to tests/fixtures/preprocessor/question-use-docker-unknown.json
diff --git a/tests/fixtures/precompiler/quoted-exact-use-docker-backtick-unknown.json b/tests/fixtures/preprocessor/quoted-exact-use-docker-backtick-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/quoted-exact-use-docker-backtick-unknown.json
rename to tests/fixtures/preprocessor/quoted-exact-use-docker-backtick-unknown.json
diff --git a/tests/fixtures/precompiler/quoted-exact-use-docker-single-unknown.json b/tests/fixtures/preprocessor/quoted-exact-use-docker-single-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/quoted-exact-use-docker-single-unknown.json
rename to tests/fixtures/preprocessor/quoted-exact-use-docker-single-unknown.json
diff --git a/tests/fixtures/precompiler/quoted-exact-use-docker-unknown.json b/tests/fixtures/preprocessor/quoted-exact-use-docker-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/quoted-exact-use-docker-unknown.json
rename to tests/fixtures/preprocessor/quoted-exact-use-docker-unknown.json
diff --git a/tests/fixtures/precompiler/quoted-reported-unknown.json b/tests/fixtures/preprocessor/quoted-reported-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/quoted-reported-unknown.json
rename to tests/fixtures/preprocessor/quoted-reported-unknown.json
diff --git a/tests/fixtures/precompiler/unsupported-alias-unknown.json b/tests/fixtures/preprocessor/unsupported-alias-unknown.json
similarity index 100%
rename from tests/fixtures/precompiler/unsupported-alias-unknown.json
rename to tests/fixtures/preprocessor/unsupported-alias-unknown.json
diff --git a/tests/test_litellm_preprocessor_model_config.py b/tests/test_litellm_preprocessor_model_config.py
index 190689b..3858f2c 100644
--- a/tests/test_litellm_preprocessor_model_config.py
+++ b/tests/test_litellm_preprocessor_model_config.py
@@ -52,7 +52,7 @@ def _completion(**kwargs):
 
     monkeypatch.setattr(module, "_get_litellm_completion", lambda: _completion)
     monkeypatch.setattr(module, "render_prompt", lambda *_: "prompt")
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     result = module._llm_fallback_precompile("please use docker", None)
 
@@ -75,7 +75,7 @@ def _completion(**kwargs):
 
     monkeypatch.setattr(module, "_get_litellm_completion", lambda: _completion)
     monkeypatch.setattr(module, "render_prompt", lambda *_: "prompt")
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     result = module._llm_fallback_precompile("please use docker", None)
 
@@ -100,7 +100,7 @@ def _completion(**kwargs):
 
     monkeypatch.setattr(module, "_get_litellm_completion", lambda: _completion)
     monkeypatch.setattr(module, "render_prompt", lambda *_: "prompt")
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     result = module._llm_fallback_precompile("please use docker", None)
 
@@ -125,7 +125,7 @@ def _completion(**kwargs):
 
     monkeypatch.setattr(module, "_get_litellm_completion", lambda: _completion)
     monkeypatch.setattr(module, "render_prompt", lambda *_: "prompt")
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     result = module._llm_fallback_precompile("please use docker", None)
 
diff --git a/tests/test_openwebui_preprocessor_pipe.py b/tests/test_openwebui_preprocessor_pipe.py
index 0132212..c09059b 100644
--- a/tests/test_openwebui_preprocessor_pipe.py
+++ b/tests/test_openwebui_preprocessor_pipe.py
@@ -184,7 +184,7 @@ async def _chat_completion(_: object, payload: dict[str, Any], __: object) -> di
         "outcome": module.PRECOMPILE_OUTCOME_DIRECTIVE,
         "directive": "use docker",
     }
-    module.parse_precompiler_output = lambda value, **_kwargs: value
+    module.parse_preprocessor_output = lambda value, **_kwargs: value
 
     result = asyncio.run(
         pipe.pipe(
@@ -533,7 +533,7 @@ def _create_engine():
 
     monkeypatch.setattr(module, "create_engine", _create_engine)
     monkeypatch.setattr(module, "precompile_heuristic", lambda _text: {"outcome": "no_directive"})
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     pipe = module.Pipe()
     pipe.valves.BASE_MODEL_ID = "base-model"
@@ -592,7 +592,7 @@ def test_preprocessor_pipe_normal_update_forwards_with_state_and_persists_checkp
             }
         ),
     )
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     forwarded_payloads: list[dict[str, object]] = []
 
@@ -1122,7 +1122,7 @@ async def _chat_completion(_: object, payload: dict[str, Any], __: object) -> di
 
     monkeypatch.setattr(module, "generate_chat_completion", _chat_completion)
     monkeypatch.setattr(module, "precompile_heuristic", lambda _text: {"outcome": "no_directive"})
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     pipe = module.Pipe()
     pipe.valves.BASE_MODEL_ID = "base-model"
@@ -1158,7 +1158,7 @@ async def _chat_completion(_: object, payload: dict[str, Any], __: object) -> di
             "directive": "prohibit peanuts",
         },
     )
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     pipe = module.Pipe()
     pipe.valves.BASE_MODEL_ID = "base-model"
@@ -1198,7 +1198,7 @@ async def _chat_completion(_: object, payload: dict[str, Any], __: object) -> di
 
     monkeypatch.setattr(module, "generate_chat_completion", _chat_completion)
     monkeypatch.setattr(module, "precompile_heuristic", lambda _text: {"outcome": "no_directive"})
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     pipe = module.Pipe()
     pipe.valves.BASE_MODEL_ID = "base-model"
@@ -1240,7 +1240,7 @@ async def _chat_completion(_: object, payload: dict[str, Any], __: object) -> An
 
     monkeypatch.setattr(module, "generate_chat_completion", _chat_completion)
     monkeypatch.setattr(module, "precompile_heuristic", lambda _text: {"outcome": "no_directive"})
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     pipe = module.Pipe()
     pipe.valves.BASE_MODEL_ID = "base-model"
@@ -1345,7 +1345,7 @@ def _heuristic(text: str) -> dict[str, object]:
         return {"outcome": "no_directive", "directive": None}
 
     monkeypatch.setattr(module, "precompile_heuristic", _heuristic)
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     forwarded_payloads: list[dict[str, object]] = []
 
@@ -1416,7 +1416,7 @@ def _heuristic(text: str) -> dict[str, object]:
         return {"outcome": "no_directive", "directive": None}
 
     monkeypatch.setattr(module, "precompile_heuristic", _heuristic)
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     forwarded_payloads: list[dict[str, object]] = []
 
@@ -1509,7 +1509,7 @@ def test_preprocessor_pipe_trace_update_clear_reset_paths_single_and_consistent(
         "precompile_heuristic",
         lambda _text: {"outcome": "no_directive", "directive": None},
     )
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     downstream_calls = 0
 
@@ -1566,7 +1566,7 @@ def test_preprocessor_pipe_clear_state_trace_not_duplicated_when_model_echoes_hi
         "precompile_heuristic",
         lambda _text: {"outcome": "no_directive", "directive": None},
     )
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     async def _chat_completion(
         _: object, payload: dict[str, object], __: object
@@ -1643,7 +1643,7 @@ def test_preprocessor_pipe_clear_state_strips_preexisting_contradictory_trace_fr
         "precompile_heuristic",
         lambda _text: {"outcome": "no_directive", "directive": None},
     )
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     old_trace = (
         "Context Compiler trace\n\n"
@@ -1716,7 +1716,7 @@ def test_preprocessor_pipe_update_trace_and_injection_when_heuristic_emits_direc
             else {"outcome": "no_directive", "directive": None}
         ),
     )
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     forwarded_payloads: list[dict[str, object]] = []
 
@@ -1785,7 +1785,7 @@ def test_preprocessor_pipe_replacement_update_trace_and_injection_when_heuristic
             )
         ),
     )
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     async def _chat_completion(
         _: object,
@@ -1841,7 +1841,7 @@ def test_preprocessor_pipe_ambiguous_text_passthrough_trace_streaming(monkeypatc
     module._CHECKPOINTS_BY_CHAT_KEY.clear()
 
     monkeypatch.setattr(module, "precompile_heuristic", lambda _text: {"outcome": "no_directive"})
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     class _StreamingResponse:
         def __init__(self) -> None:
@@ -1899,7 +1899,7 @@ def test_preprocessor_pipe_natural_language_abstention_can_passthrough_with_trac
 
     # Use the real heuristic behavior for this phrase (unknown/no_directive),
     # and force fallback to abstain so runtime stays conservative.
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda _value, **_kwargs: None)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda _value, **_kwargs: None)
 
     async def _chat_completion(
         _: object, payload: dict[str, object], __: object
@@ -1956,7 +1956,7 @@ def _heuristic(text: str) -> dict[str, object]:
         return {"outcome": "no_directive", "directive": None}
 
     monkeypatch.setattr(module, "precompile_heuristic", _heuristic)
-    monkeypatch.setattr(module, "parse_precompiler_output", lambda value, **_kwargs: value)
+    monkeypatch.setattr(module, "parse_preprocessor_output", lambda value, **_kwargs: value)
 
     downstream_calls = 0
 
diff --git a/tests/test_precompiler_conformance.py b/tests/test_preprocessor_conformance.py
similarity index 90%
rename from tests/test_precompiler_conformance.py
rename to tests/test_preprocessor_conformance.py
index 2916850..6b72c15 100644
--- a/tests/test_precompiler_conformance.py
+++ b/tests/test_preprocessor_conformance.py
@@ -2,14 +2,14 @@
 import re
 from pathlib import Path
 
-from experimental.preprocessor.heuristic_precompiler import precompile_heuristic
+from experimental.preprocessor.heuristic_preprocessor import precompile_heuristic
 from experimental.preprocessor.output_validation import validate_precompiler_output
 
-_PRECOMPILER_FIXTURES_DIR = Path(__file__).resolve().parent / "fixtures" / "precompiler"
+_PREPROCESSOR_FIXTURES_DIR = Path(__file__).resolve().parent / "fixtures" / "preprocessor"
 
 
 def _fixture_paths() -> list[Path]:
-    return sorted(_PRECOMPILER_FIXTURES_DIR.glob("*.json"))
+    return sorted(_PREPROCESSOR_FIXTURES_DIR.glob("*.json"))
 
 
 def _load_fixture(path: Path) -> dict[str, object]:
@@ -53,7 +53,7 @@ def _derived_risky_rewrite_candidates(source_input: str) -> list[str]:
     return candidates
 
 
-def test_precompiler_conformance_fixtures() -> None:
+def test_preprocessor_conformance_fixtures() -> None:
     for path in _fixture_paths():
         fixture = _load_fixture(path)
         expected = fixture["expected"]
@@ -71,7 +71,7 @@ def test_precompiler_conformance_fixtures() -> None:
 
 
 def test_engine_owned_near_misses_are_reject_only_for_fallback_rewrites() -> None:
-    # Engine-owned near-misses must not be canonicalized by the precompiler and
+    # Engine-owned near-misses must not be canonicalized by the preprocessor and
     # must remain unknown even if fallback proposes a plausible canonical rewrite.
     for path in _fixture_paths():
         fixture = _load_fixture(path)
diff --git a/tests/test_precompiler_heuristic.py b/tests/test_preprocessor_heuristic.py
similarity index 99%
rename from tests/test_precompiler_heuristic.py
rename to tests/test_preprocessor_heuristic.py
index 8b55649..62bf776 100644
--- a/tests/test_precompiler_heuristic.py
+++ b/tests/test_preprocessor_heuristic.py
@@ -1,6 +1,6 @@
 import pytest
 
-from experimental.preprocessor.heuristic_precompiler import precompile_heuristic
+from experimental.preprocessor.heuristic_preprocessor import precompile_heuristic
 
 
 def test_heuristic_rejects_consistent_high_risk_non_directives() -> None:
diff --git a/tests/test_precompiler_heuristic_properties.py b/tests/test_preprocessor_heuristic_properties.py
similarity index 94%
rename from tests/test_precompiler_heuristic_properties.py
rename to tests/test_preprocessor_heuristic_properties.py
index 92c9272..438a9ee 100644
--- a/tests/test_precompiler_heuristic_properties.py
+++ b/tests/test_preprocessor_heuristic_properties.py
@@ -8,10 +8,10 @@
     PRECOMPILE_OUTCOME_NO_DIRECTIVE,
     PRECOMPILE_OUTCOME_UNKNOWN,
 )
-from experimental.preprocessor.heuristic_precompiler import precompile_heuristic
+from experimental.preprocessor.heuristic_preprocessor import precompile_heuristic
 from experimental.preprocessor.output_validation import (
     _is_allowed_directive,
-    parse_precompiler_output,
+    parse_preprocessor_output,
 )
 
 CANONICAL_DIRECTIVES = [
@@ -48,7 +48,7 @@ def test_heuristic_accepts_canonical_directive_with_trailing_period_or_bang(
 ) -> None:
     result = precompile_heuristic(f"{directive}{punctuation}")
     assert result["outcome"] == PRECOMPILE_OUTCOME_DIRECTIVE
-    parsed = parse_precompiler_output(result["directive"])
+    parsed = parse_preprocessor_output(result["directive"])
     assert parsed == result["directive"]
 
 
@@ -66,7 +66,7 @@ def test_heuristic_accepts_single_layer_exact_wrapper(
     left, right = wrapper
     result = precompile_heuristic(f"{left}{directive}{right}")
     assert result["outcome"] == PRECOMPILE_OUTCOME_DIRECTIVE
-    parsed = parse_precompiler_output(result["directive"])
+    parsed = parse_preprocessor_output(result["directive"])
     assert parsed == result["directive"]
 
 
@@ -109,7 +109,7 @@ def test_heuristic_directive_output_is_always_validator_safe(message: str) -> No
         return
     directive = result["directive"]
     assert isinstance(directive, str)
-    assert parse_precompiler_output(directive) == directive
+    assert parse_preprocessor_output(directive) == directive
 
 
 @given(st.sampled_from(CANONICAL_DIRECTIVES), NON_EMPTY_TEXT, NON_EMPTY_TEXT)
diff --git a/tests/test_precompiler_output_validation.py b/tests/test_preprocessor_output_validation.py
similarity index 100%
rename from tests/test_precompiler_output_validation.py
rename to tests/test_preprocessor_output_validation.py
diff --git a/tests/test_precompiler_validator_properties.py b/tests/test_preprocessor_validator_properties.py
similarity index 90%
rename from tests/test_precompiler_validator_properties.py
rename to tests/test_preprocessor_validator_properties.py
index 989a131..8a30631 100644
--- a/tests/test_precompiler_validator_properties.py
+++ b/tests/test_preprocessor_validator_properties.py
@@ -3,7 +3,7 @@
 
 from experimental.preprocessor.output_validation import (
     _is_allowed_directive,
-    parse_precompiler_output,
+    parse_preprocessor_output,
     validate_precompiler_output,
 )
 
@@ -45,14 +45,14 @@
     )
 )
 def test_parse_non_string_never_produces_directive(raw_output: object) -> None:
-    assert parse_precompiler_output(raw_output) is None
+    assert parse_preprocessor_output(raw_output) is None
 
 
 @given(NOISY_TEXT)
 def test_parse_invalid_text_never_becomes_directive(text: str) -> None:
     stripped = text.strip()
     assume(not _is_allowed_directive(stripped))
-    assert parse_precompiler_output(text) is None
+    assert parse_preprocessor_output(text) is None
 
 
 @given(st.sampled_from(CANONICAL_DIRECTIVES), SPACE_TEXT, SPACE_TEXT)
@@ -60,7 +60,7 @@ def test_parse_valid_canonical_directive_always_passes(
     directive: str, leading_ws: str, trailing_ws: str
 ) -> None:
     raw = f"{leading_ws}{directive}{trailing_ws}"
-    assert parse_precompiler_output(raw) == directive
+    assert parse_preprocessor_output(raw) == directive
 
 
 @given(st.sampled_from(CANONICAL_DIRECTIVES), NON_EMPTY_TEXT, NON_EMPTY_TEXT)
@@ -70,7 +70,7 @@ def test_parse_rejects_directive_with_surrounding_text(
     raw = f"{prefix} {directive} {suffix}"
     stripped = raw.strip()
     assume(not _is_allowed_directive(stripped))
-    assert parse_precompiler_output(raw) is None
+    assert parse_preprocessor_output(raw) is None
 
 
 @given(
@@ -87,7 +87,7 @@ def test_parse_rejects_directive_with_surrounding_text(
 )
 def test_parse_rejects_directive_in_constrained_wrappers(directive: str, wrapper: str) -> None:
     wrapped = wrapper.format(directive)
-    assert parse_precompiler_output(wrapped) is None
+    assert parse_preprocessor_output(wrapped) is None
 
 
 def test_validate_malformed_abstain_negative_boundaries_are_unknown() -> None:
@@ -116,13 +116,13 @@ def test_parse_rejects_near_miss_directives_when_wrapped_or_prefixed() -> None:
         'he said "use docker"',
     ]
     for raw in cases:
-        assert parse_precompiler_output(raw) is None
+        assert parse_preprocessor_output(raw) is None
 
 
 @given(st.one_of(st.none(), st.integers(), st.text(max_size=120)))
 def test_parse_output_idempotent(raw_output: object) -> None:
-    first = parse_precompiler_output(raw_output)
-    second = parse_precompiler_output(first)
+    first = parse_preprocessor_output(raw_output)
+    second = parse_preprocessor_output(first)
     if first is None:
         assert second is None
     else:
diff --git a/tests/test_repl.py b/tests/test_repl.py
index 957f15a..42ca966 100644
--- a/tests/test_repl.py
+++ b/tests/test_repl.py
@@ -303,9 +303,9 @@ def _parse(raw_output: object, *, source_input: str | None = None) -> str | None
         seen.append((raw_output, source_input))
         if raw_output == "use podman instead of docker":
             return "use podman instead of docker"
-        raise AssertionError("parse_precompiler_output should be bypassed while pending")
+        raise AssertionError("parse_preprocessor_output should be bypassed while pending")
 
-    monkeypatch.setattr(repl_module, "parse_precompiler_output", _parse)
+    monkeypatch.setattr(repl_module, "parse_preprocessor_output", _parse)
 
     out = StringIO()
     run_repl(
@@ -323,9 +323,9 @@ def _parse(raw_output: object, *, source_input: str | None = None) -> str | None
 def test_repl_without_precompiler_does_not_parse_inputs(monkeypatch: pytest.MonkeyPatch) -> None:
     def _fail_parse(_raw: object, *, source_input: str | None = None) -> str | None:
         del source_input
-        raise AssertionError("parse_precompiler_output should not be called")
+        raise AssertionError("parse_preprocessor_output should not be called")
 
-    monkeypatch.setattr(repl_module, "parse_precompiler_output", _fail_parse)
+    monkeypatch.setattr(repl_module, "parse_preprocessor_output", _fail_parse)
 
     out = StringIO()
     run_repl(StringIO('{"classification":"directive","output":"prohibit peanuts"}\nquit\n'), out)
diff --git a/uv.lock b/uv.lock
index 16d5b5f..bfdfa14 100644
--- a/uv.lock
+++ b/uv.lock
@@ -468,7 +468,7 @@ wheels = [
 
 [[package]]
 name = "context-compiler"
-version = "0.6.15"
+version = "0.6.16"
 source = { editable = "." }
 
 [package.optional-dependencies]