feat: 添加架构约束和编码规范文档，增强项目文档的完整性

.ccw/specs/architecture-constraints.md

@@ -0,0 +1,6 @@
+# Architecture Constraints
+
+## Schema Evolution
+
+- [compatibility] When enhancing existing schemas, use optional fields and additionalProperties rather than creating new schemas. Avoid breaking changes.
+- [portability] Use relative paths for cross-artifact navigation to ensure portability across different environments and installations.

.ccw/specs/coding-conventions.md

@@ -0,0 +1,17 @@
+# Coding Conventions
+
+## Navigation & Path Handling
+
+- [navigation] When creating navigation links between artifacts, always compute relative paths from the artifact's actual location, not from an assumed location. Test path resolution before committing. (learned: 2026-03-07)
+- [schema] Always include schema_version field in index/registry files to enable safe evolution and migration detection. (learned: 2026-03-07)
+- [error-handling] When adding version checks or validation, always continue with degraded functionality rather than failing hard. Log warnings but don't block execution. (learned: 2026-03-07)
+
+## Document Generation
+
+- [architecture] For document generation systems, adopt Layer 3→2→1 pattern (components → features → indexes) for efficient incremental updates. (learned: 2026-03-07)
+
+## Implementation Quality
+
+- [validation] Path calculation errors are subtle and hard to spot in static review. Always verify path resolution from the actual file location, not from documentation. (learned: 2026-03-07)
+- [implementation] Declaring "add X to Y" in documentation is not enough - the actual logic must be implemented in the target files. (learned: 2026-03-07)
+- [clarity] Explicit instructions are better than implicit ones. Vague instructions like "Update _index.md files" should be made explicit (e.g., "Update sessions/_index.md"). (learned: 2026-03-07)

.npmignore

@@ -17,6 +17,7 @@
 
 # Workflow runtime data
 .workflow/
+.ccw/
 
 # Test files
 test/

codex-lens/src/codexlens/storage/deepwiki_store.py

@@ -1031,6 +1031,10 @@ class DeepWikiStore:
         Returns:
             Staleness score between 0.0 and 1.0.
         """
+        # Deleted symbols are maximally stale
+        if is_deleted:
+            return 1.0
+
         w_t, w_c, w_s = weights
 
         # T: Time decay factor
@@ -1045,9 +1049,6 @@ class DeepWikiStore:
         C = 1 / (1 + math.exp(-churn_raw + 3))  # sigmoid centered at 3
 
         # M: Symbol modification factor
-        if is_deleted:
-            M = 1.0
-        else:
         M = min(1.0, max(0.0, proportion_changed))
 
         return min(1.0, w_t * T + w_c * C + w_s * M)