diff --git a/.claude/commands/dev-checklists.md b/.claude/commands/dev-checklists.md
index 342118a..a4dc87e 100644
--- a/.claude/commands/dev-checklists.md
+++ b/.claude/commands/dev-checklists.md
@@ -46,9 +46,13 @@ When implementing or modifying code that affects statistical methodology (estima
    - [ ] For edge cases: either match reference OR document deviation
 
 3. **When deviating from reference implementations**:
-   - [ ] Add a **Note** in the Methodology Registry explaining the deviation
+   - [ ] Add entry in `docs/methodology/REGISTRY.md` using a reviewer-recognized label:
+         `**Note:**`, `**Deviation from R:**`, or `**Note (deviation from R):**`
+         (see CLAUDE.md "Documenting Deviations" for full format reference)
    - [ ] Include rationale (e.g., "defensive enhancement", "R errors here")
    - [ ] Ensure the deviation is an improvement, not a bug
+   - [ ] If deferring P2/P3 work: add row to `TODO.md` table under "Tech Debt from Code
+         Reviews" with columns `Issue | Location | PR | Priority`
 
 4. **Testing methodology-aligned behavior**:
    - [ ] Test that edge cases produce documented behavior (NaN, warning, etc.)
diff --git a/.claude/commands/pre-merge-check.md b/.claude/commands/pre-merge-check.md
index fca6e07..0454d83 100644
--- a/.claude/commands/pre-merge-check.md
+++ b/.claude/commands/pre-merge-check.md
@@ -107,6 +107,20 @@ git diff HEAD -- <changed-py-files> | grep "^+.*def " | head -10
 
 For each changed function, flag: "Verify docstring Parameters section matches updated signature for: `<function_name>`"
 
+#### 2.5 Methodology Documentation Check
+
+If any methodology files changed, check whether `docs/methodology/REGISTRY.md` was also
+modified in the changed file set (from Section 1).
+
+If methodology files changed but REGISTRY.md was NOT modified, flag:
+"Methodology files changed but `docs/methodology/REGISTRY.md` was not updated. If your
+changes deviate from reference implementations, document them using a reviewer-recognized
+label (`**Note:**`, `**Deviation from R:**`, or `**Note (deviation from R):**`) —
+undocumented deviations are flagged as P1 by the AI reviewer and cannot be mitigated
+by TODO.md."
+
+This is a WARNING, not a blocker — not every methodology change involves a deviation.
+
 ### 3. Display Context-Specific Checklist
 
 Based on what changed, display the appropriate checklist items:
@@ -134,6 +148,11 @@ Based on your changes to: <list of changed files>
 - [ ] Control group composition verified for new code paths
 - [ ] "Not-yet-treated" excludes the treatment cohort itself
 - [ ] Parameter interactions tested with all aggregation methods
+
+### Methodology Deviation Documentation
+- [ ] If deviating from reference implementation: added a reviewer-recognized label
+      (`**Note:**`, `**Deviation from R:**`, or `**Note (deviation from R):**`) in REGISTRY.md
+- [ ] No undocumented methodology deviations (AI reviewer flags these as P1)
 ```
 
 #### If Documentation Files Changed
@@ -141,7 +160,6 @@ Based on your changes to: <list of changed files>
 ### Documentation Sync
 - [ ] Docstrings updated for changed function signatures
 - [ ] README updated if user-facing behavior changes
-- [ ] REGISTRY.md updated if methodology edge cases change
 ```
 
 #### If This Appears to Be a Bug Fix
diff --git a/CLAUDE.md b/CLAUDE.md
index 4e0db93..c66c721 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -91,6 +91,29 @@ pytest tests/test_rust_backend.py -v
    Standalone estimators must be updated individually.
 8. **Dependencies**: numpy, pandas, and scipy ONLY. No statsmodels.
 
+## Documenting Deviations (AI Review Compatibility)
+
+The AI PR reviewer recognizes deviations as documented (and downgrades them to P3) ONLY
+when they use specific label patterns in `docs/methodology/REGISTRY.md`. Using different
+wording will cause a P1 finding ("undocumented methodology deviation").
+
+**Recognized REGISTRY.md labels** — use one of these in the relevant estimator section:
+
+| Label | When to use | Example |
+|-------|------------|---------|
+| `- **Note:** <text>` | Defensive enhancements, implementation choices | `- **Note:** Defensive enhancement matching CallawaySantAnna NaN convention` |
+| `- **Deviation from R:** <text>` | Intentional differences from R packages | `- **Deviation from R:** R's fixest uses t-distribution at all levels` |
+| `**Note (deviation from R):** <text>` | Combined form, inline within edge case bullets | See SyntheticDiD section in REGISTRY.md |
+
+**TODO.md format** — for deferring P2/P3 items only (P0/P1 cannot be deferred):
+
+Add a row to the table in `TODO.md` under "Tech Debt from Code Reviews" in the appropriate
+category (`Methodology/Correctness`, `Performance`, or `Testing/Docs`):
+
+| Issue | Location | PR | Priority |
+|-------|----------|----|----------|
+| Description of deferred item | `file.py` | #NNN | Medium/Low |
+
 ## Testing Conventions
 
 - **`ci_params` fixture** (session-scoped in `conftest.py`): Use `ci_params.bootstrap(n)` and