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@@ -125,3 +125,54 @@ substituted into the same FE interaction framework.
 - `gap_neg` = 0.4993 (p = 0.0027)
 
 These estimates are not part of the current notebook's identified model scope and should not be interpreted as a completed reaction-function test in this manuscript version.
+
+## A10. Estimation Workflow and Test Inventory
+
+### Border treatment construction
+
+Two border definitions were used:
+
+1. District-level baseline treatment (`border_district`), with border-adjacent districts coded as `01`, `02`, `06`, `08`, `8A`, `09`, `10`.
+2. Well-level proximity treatment, rolled up to district-year exposure.
+
+Well-level proximity workflow:
+
+1. Import TX-MX proximity flags from `WellAnalyzer` (`within_25km_texmex`, `within_50km_texmex`).
+2. Build additional TX-NM, TX-OK, TX-LA border segments from county boundary geometry plus seed lines.
+3. Compute distances in EPSG:5070 and generate threshold flags.
+4. Build composite indicators:
+   - `within_50km_state_border_any`
+   - `well_border_exposed` (within 50 km of TX-MX or any TX-state border segment).
+
+District-year exposure share:
+$$
+ShareBorder_{dt} = \frac{BorderExposedInspections_{dt}}{Inspections_{dt}}
+$$
+Alternative district coding:
+$$
+border\_exposure\_district_{dt} = \mathbb{1}[ShareBorder_{dt} \ge 0.25]
+$$
+
+### Tests run
+
+1. Descriptive border-gap comparisons by group means.
+2. RQ1 levels regressions:
+   - Outcomes: `inspection_intensity`, `violations_per_inspection`.
+   - Model: `border_district + log_unique_wells + C(year)`.
+3. RQ2 FE interaction regressions:
+   - Outcomes: `inspection_intensity`, `violations_per_inspection`, `avg_days_to_enforcement`, `resolution_rate`.
+   - Model: `C(district) + C(year) + post_2019:border_district + post_trend:border_district`.
+4. Border-type robustness:
+   - District border-type profile (`TX-MX`, `TX-NM`, `TX-OK`, `TX-LA`).
+   - RQ1-style levels with `has_tx_*`.
+   - RQ2-style FE interactions with `post_2019:has_tx_*` and `post_trend:has_tx_*`.
+5. Continuous exposure robustness:
+   - Replace binary border term with `share_border_exposed_insp` in RQ1-style and RQ2-style specifications.
+6. Cutoff sensitivity robustness:
+   - Recompute exposure using minimum distance to any border at 25/75/100 km.
+   - Estimate RQ1-style inspection-intensity models and RQ2-style timing interaction models.
+7. Figures/reporting:
+   - Border vs non-border trend plots.
+   - Main timing figure with district-year means and 95% CIs.
+8. Reaction-function scaffolding (not estimated):
+   - Create district-competitor link table and district-year competitor template for future data integration.