(mess) Stuffing commit.

docs/chaos.md

@@ -10,11 +10,10 @@ Chaos testing applies the invariant-driven verification approach from [Invariant
 const result = await fastify.apophis.contract({
   runs: 50,
   chaos: {
-    probability: 0.1,  // 10% of requests get chaos
-    delay: { probability: 1, minMs: 100, maxMs: 500 },
-    error: { probability: 1, statusCode: 503 },
-    dropout: { probability: 1 },
-    corruption: { probability: 1 },
+    delay: { probability: 0.1, minMs: 100, maxMs: 500 },
+    error: { probability: 0.1, statusCode: 503 },
+    dropout: { probability: 0.05 },
+    corruption: { probability: 0.1 },
   },
 });
 ```
@@ -26,7 +25,6 @@ const result = await fastify.apophis.contract({
 Adds artificial latency. Tests timeout contracts:
 
 ```apostl
-timeout_occurred(this) == false
 response_time(this) < 1000
 ```
 
@@ -37,7 +35,8 @@ response_time(this) < 1000
 Forces HTTP status codes. Tests error-handling contracts:
 
 ```apostl
-if status:503 then response_body(this).retry_after != null
+// Behavioral: when the service is unavailable, the client receives a valid retry signal
+if status:503 then response_headers(this).retry-after > 0
 ```
 
 ### Dropout
@@ -45,7 +44,8 @@ if status:503 then response_body(this).retry_after != null
 Simulates network failure (status 0). Tests fallback contracts:
 
 ```apostl
-status:200 || status:0
+// Behavioral: partial failure must still return previously cached data
+if status:0 then response_body(this).cached_data == previous(response_body(GET /cache/{request_params(this).key}))
 ```
 
 ### Corruption
@@ -53,7 +53,8 @@ status:200 || status:0
 Mutates response bodies. Tests parsing robustness:
 
 ```apostl
-response_body(this).id != null
+// Behavioral: corrupted requests maintain traceability for debugging
+if status:400 then response_body(this).request_id == request_headers(this).x-request-id
 ```
 
 ## Corruption Strategies
@@ -104,7 +105,7 @@ Failed tests include chaos events in diagnostics:
 ```json
 {
   "statusCode": 503,
-  "error": "Contract violation: status:200",
+  "error": "Contract violation: if status:503 then response_headers(this).retry-after > 0",
   "chaosEvents": [
     {
       "type": "error",
@@ -122,7 +123,7 @@ Failed tests include chaos events in diagnostics:
 
 1. **Start small**: `probability: 0.05` (5% of requests)
 2. **Test one failure mode at a time**: Comment out other chaos types
-3. **Verify contracts handle chaos**: `if status:503 then response_body(this).error != null`
+3. **Verify contracts handle chaos**: `if status:503 then response_code(GET /health) == 200`
 4. **Use seeds for reproducibility**: `seed: 42` makes chaos deterministic
 
 ## Example: Testing Retry Logic
@@ -131,7 +132,7 @@ Failed tests include chaos events in diagnostics:
 fastify.get('/data', {
   schema: {
     'x-ensures': [
-      'if status:503 then response_headers(this).retry-after != null',
+      'if status:503 then response_headers(this).retry-after > 0',
       'redirect_count(this) <= 3',
     ],
   },
@@ -140,8 +141,7 @@ fastify.get('/data', {
 // Test
 const result = await fastify.apophis.contract({
   chaos: {
-    probability: 0.2,
-    error: { probability: 1, statusCode: 503 },
+    error: { probability: 0.2, statusCode: 503 },
   },
 });
 ```