feat: add snapshot-by-processorId endpoint for robust processor lookup

Add GET /executions/{id}/processors/by-id/{processorId}/snapshot endpoint
that fetches processor snapshot data by processorId instead of positional
index, which is fragile when the tree structure changes. The existing
index-based endpoint remains unchanged for backward compatibility.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cameleer3-server-app/src/main/java/com/cameleer3/server/app/controller/DetailController.java

@@ -49,7 +49,7 @@ public class DetailController {
     }
 
     @GetMapping("/{executionId}/processors/{index}/snapshot")
-    @Operation(summary = "Get exchange snapshot for a specific processor")
+    @Operation(summary = "Get exchange snapshot for a specific processor by index")
     @ApiResponse(responseCode = "200", description = "Snapshot data")
     @ApiResponse(responseCode = "404", description = "Snapshot not found")
     public ResponseEntity<Map<String, String>> getProcessorSnapshot(
@@ -69,4 +69,16 @@ public class DetailController {
 
         return ResponseEntity.ok(snapshot);
     }
+
+    @GetMapping("/{executionId}/processors/by-id/{processorId}/snapshot")
+    @Operation(summary = "Get exchange snapshot for a specific processor by processorId")
+    @ApiResponse(responseCode = "200", description = "Snapshot data")
+    @ApiResponse(responseCode = "404", description = "Snapshot not found")
+    public ResponseEntity<Map<String, String>> processorSnapshotById(
+            @PathVariable String executionId,
+            @PathVariable String processorId) {
+        return detailService.getProcessorSnapshot(executionId, processorId)
+            .map(ResponseEntity::ok)
+            .orElse(ResponseEntity.notFound().build());
+    }
 }

cameleer3-server-app/src/main/java/com/cameleer3/server/app/storage/PostgresExecutionStore.java

@@ -121,6 +121,13 @@ public class PostgresExecutionStore implements ExecutionStore {
                 PROCESSOR_MAPPER, executionId);
     }
 
+    @Override
+    public Optional<ProcessorRecord> findProcessorById(String executionId, String processorId) {
+        String sql = "SELECT * FROM processor_executions WHERE execution_id = ? AND processor_id = ? LIMIT 1";
+        List<ProcessorRecord> results = jdbc.query(sql, PROCESSOR_MAPPER, executionId, processorId);
+        return results.isEmpty() ? Optional.empty() : Optional.of(results.get(0));
+    }
+
     private static final RowMapper<ExecutionRecord> EXECUTION_MAPPER = (rs, rowNum) ->
             new ExecutionRecord(
                     rs.getString("execution_id"), rs.getString("route_id"),

cameleer3-server-core/src/main/java/com/cameleer3/server/core/detail/DetailService.java

@@ -38,6 +38,18 @@ public class DetailService {
                 });
     }
 
+    public Optional<Map<String, String>> getProcessorSnapshot(String executionId, String processorId) {
+        return executionStore.findProcessorById(executionId, processorId)
+            .map(p -> {
+                Map<String, String> snapshot = new LinkedHashMap<>();
+                if (p.inputBody() != null) snapshot.put("inputBody", p.inputBody());
+                if (p.outputBody() != null) snapshot.put("outputBody", p.outputBody());
+                if (p.inputHeaders() != null) snapshot.put("inputHeaders", p.inputHeaders());
+                if (p.outputHeaders() != null) snapshot.put("outputHeaders", p.outputHeaders());
+                return snapshot;
+            });
+    }
+
     List<ProcessorNode> buildTree(List<ProcessorRecord> processors) {
         if (processors.isEmpty()) return List.of();
 

cameleer3-server-core/src/main/java/com/cameleer3/server/core/storage/ExecutionStore.java

@@ -16,6 +16,8 @@ public interface ExecutionStore {
 
     List<ProcessorRecord> findProcessors(String executionId);
 
+    Optional<ProcessorRecord> findProcessorById(String executionId, String processorId);
+
     record ExecutionRecord(
             String executionId, String routeId, String agentId, String applicationName,
             String status, String correlationId, String exchangeId,