Replace paraphrased constitution with the 1224-line master.

Copy CODING_CONSTITUTION.md from the AgentStore docs/development path and split
the seven always-on .mdc files from that exact text.

.cursor/rules/40-testing.mdc

@@ -2,15 +2,146 @@
 alwaysApply: true
 ---
 
-# Periscope Cursor Engineering Rules
+# 21. TESTING IS MANDATORY
 
-Mandatory for every Cursor agent working on Periscope. This section is copied from `docs/development/CODING_CONSTITUTION.md` and must not contradict that master.
+Every meaningful implementation change requires tests.
 
-## 4. Testing
+At minimum test:
+
+```text
+normal case
+failure case
+boundary case
+insufficient evidence
+```
+
+For semantic models, also test the boundaries between object types.
+
+For PCB analysis, explicitly test:
+
+```text
+Pad
+Via
+Track
+Zone
+```
+
+as distinct semantic entities.
+
+---
+
+# 22. TESTS MUST BE STRICT AND ABSOLUTE
+
+Periscope tests are not advisory.
+
+A test must define the exact expected behavior.
+
+Do not use vague assertions such as:
+
+```text
+result is reasonable
+result is not empty
+analysis completed
+```
+
+when an exact result can be established.
+
+Prefer assertions such as:
+
+```text
+expected object type == Via
+expected pad count == 24
+expected finding count == 0
+expected finding code == X
+expected severity == ERROR
+expected confidence == HIGH
+```
+
+Where deterministic exact values are available, test them exactly.
+
+Do not weaken tests merely to make an implementation pass.
+
+Do not modify expected results to accommodate incorrect implementation behavior.
+
+---
+
+# 23. REGRESSION TEST FOR EVERY BUG
+
+Every fixed bug must become a regression test.
+
+Required sequence:
+
+```text
+BUG
+ ↓
+REPRODUCE
+ ↓
+TEST FAILS
+ ↓
+FIX
+ ↓
+TEST PASSES
+ ↓
+FULL REGRESSION
+```
+
+A bug fix is not complete until the original failure is permanently represented by a test.
+
+---
+
+# 24. TEST THE NEGATIVE CASE
+
+Do not test only:
+
+```text
+valid → pass
+```
+
+Also test:
+
+```text
+invalid → fail
+```
+
+and ensure that genuine errors remain detectable.
+
+For example, if fixing:
+
+```text
+24 datasheet pins
+24 footprint pads
+N vias
+```
+
+verify that:
+
+```text
+24 datasheet pins
+23 footprint pads
+```
+
+still produces a real mismatch.
+
+The fix must remove false positives without suppressing true positives.
+
+---
+
+# 26. NO WEAKENING TESTS TO CLOSE A PHASE
+
+Do not:
+
+* delete failing tests;
+* weaken assertions;
+* skip tests;
+* mark tests expected-to-fail;
+* suppress failures;
+* change expected values without engineering justification;
+
+simply to make a macro-phase pass.
+
+If a test exposes a real implementation problem, fix the implementation.
+
+If the requirement itself is wrong, change the requirement explicitly and document why.
+
+---
 
-- Write tests before considering a slice done. Prefer tests that lock behavior (graph topology, finding codes, via≠pad, review isolation) over tests that assert overlay stamps or file provenance comments.
-- `pytest` from the worktree with the project venv. Do not claim green from a system Python missing deps.
-- One malformed IC must not kill the whole review; keep per-IC isolation tests.
-- Do not add tests whose only job is to require `Native Periscope overlay` in a copied file.
-- UI changes: exercise the flow (not a single screenshot). If no browser tools, say what was not verified.
-- Installing docs/rules is a docs phase: existence and internal consistency of the seven `.mdc` files plus this master is the check. There is no product pytest gate for markdown-only.