feat(graph): add staticGated edge property

Adds an optional `staticGated?: boolean` field to `GraphRelationship`
that flags edges originating in code branches known at index time to
be unreachable in production — e.g. `if (CONST_FALSE)` blocks where
the condition reduces to a comptime-known `false`.

Schema + persistence wiring:

- `gitnexus-shared/src/graph/types.ts` — additive optional field on
  `GraphRelationship`; absent edges read identically to live ones.
- `gitnexus/src/core/lbug/schema.ts` — `staticGated BOOLEAN` column
  on the `CodeRelation` REL table.
- `gitnexus/src/core/lbug/csv-generator.ts` — appends a
  `staticGated` column (0/1) to the `relations.csv` written for
  bulk COPY ingest.
- `gitnexus/src/core/lbug/lbug-adapter.ts` — fallback per-row
  `MATCH ... CREATE` insert reads the optional column and threads
  it into the relationship properties.

No language has populated this field yet — the Zig hookup lands in
the next commit. Existing DBs need a re-index for the new column to
appear; existing readers are unchanged because the field is
optional and absent on every other language's edges.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
(cherry picked from commit c8cd5efe27a77a5d1b3f05e3f4e89069b5c6b19e)

gitnexus-shared/src/graph/types.ts

@@ -306,4 +306,18 @@ export interface GraphRelationship {
     readonly weight: number;
     readonly note?: string;
   }[];
+  /**
+   * When `true`, the edge originates inside a code branch known at
+   * index time to be unreachable in production — e.g. a Zig
+   * `if (CONST_FALSE)` block where the condition reduces to a
+   * comptime-known `false`.  Consumers of impact / context queries
+   * can filter these edges out to suppress paper-tiger callers
+   * caused by feature-flag-gated dead code paths.
+   *
+   * Optional and additive: edges from languages that don't compute
+   * static gating leave this `undefined`, which existing readers
+   * treat identically to "live".  Currently set only by the Zig
+   * call-extractor.
+   */
+  staticGated?: boolean;
 }

gitnexus/src/core/lbug/csv-generator.ts

@@ -396,7 +396,7 @@ class BufferedCSVWriter {
 
 /** Canonical relationship CSV header — shared by the emit pass and the
  * `splitRelCsvByLabelPair` differential oracle. */
-export const REL_CSV_HEADER = 'from,to,type,confidence,reason,step';
+export const REL_CSV_HEADER = 'from,to,type,confidence,reason,step,staticGated';
 
 /** Build the escaped CSV row (no trailing newline) for one relationship.
  * Single source of the relationship row bytes — used by the emit pass and by
@@ -409,6 +409,10 @@ export const buildRelRow = (rel: GraphRelationship): string =>
     escapeCSVNumber(rel.confidence, 1.0),
     escapeCSVField(rel.reason),
     escapeCSVNumber(rel.step, 0),
+    // `staticGated` persists as 0/1 (LadybugDB BOOLEAN COPY accepts both).
+    // Every edge that does not carry the flag writes 0, so readers treat
+    // absence and `false` identically.
+    rel.staticGated === true ? '1' : '0',
   ].join(',');
 
 /** Canonical BasicBlock node CSV header — taint/PDG substrate (issue #2080).

gitnexus/src/core/lbug/lbug-adapter.ts

@@ -1466,22 +1466,28 @@ export const fallbackRelationshipInserts = async (
   for (let i = 1; i < validRelLines.length; i++) {
     const line = validRelLines[i];
     try {
-      const match = line.match(/"([^"]*)","([^"]*)","([^"]*)",([0-9.]+),"([^"]*)",([0-9-]+)/);
+      // CSV layout: from,to,type,confidence,reason,step[,staticGated]
+      // The trailing `staticGated` column (0/1) is optional so we remain
+      // tolerant of legacy CSVs written before the column existed.
+      const match = line.match(
+        /"([^"]*)","([^"]*)","([^"]*)",([0-9.]+),"([^"]*)",([0-9-]+)(?:,([01]))?/,
+      );
       if (!match) continue;
-      const [, fromId, toId, relType, confidenceStr, reason, stepStr] = match;
+      const [, fromId, toId, relType, confidenceStr, reason, stepStr, gatedStr] = match;
       const fromLabel = getNodeLabel(fromId);
       const toLabel = getNodeLabel(toId);
       if (!validTables.has(fromLabel) || !validTables.has(toLabel)) continue;
 
       const confidence = parseFloat(confidenceStr) || 1.0;
       const step = parseInt(stepStr) || 0;
+      const staticGated = gatedStr === '1';
 
       await queryAndDrain(
         conn,
         `
         MATCH (a:${escapeLabel(fromLabel)} {id: ${formatCypherValue(fromId)} }),
               (b:${escapeLabel(toLabel)} {id: ${formatCypherValue(toId)} })
-        CREATE (a)-[:${REL_TABLE_NAME} {type: ${formatCypherValue(relType)}, confidence: ${confidence}, reason: ${formatCypherValue(reason)}, step: ${step}}]->(b)
+        CREATE (a)-[:${REL_TABLE_NAME} {type: ${formatCypherValue(relType)}, confidence: ${confidence}, reason: ${formatCypherValue(reason)}, step: ${step}, staticGated: ${staticGated}}]->(b)
       `,
       );
     } catch {

gitnexus/src/core/lbug/schema.ts

@@ -657,7 +657,8 @@ ${generatedPairDdl()},
   type STRING,
   confidence DOUBLE,
   reason STRING,
-  step INT32
+  step INT32,
+  staticGated BOOLEAN
 )`;
 
 // ============================================================================