diff --git a/API.md b/API.md
index cd8ce66..9c9dae7 100644
--- a/API.md
+++ b/API.md
@@ -153,6 +153,8 @@ Performs a structural comparison between the contract definition and observed su
 - `warning`: Non-critical issue that may indicate drift
 - `info`: Informational difference
 
+Includes traceability fields.
+
 **Drift Risks Detected:**
 - `diff-noise`: Formatting-only or reorder-only changes filtered
 - `semantic-ambiguity`: Diff entries lack rule/clause references
@@ -212,6 +214,9 @@ Performs a structural comparison between the contract definition and observed su
       "contractValue": "unknown",
       "observedValue": "unknown",
       "rule": "string",
+      "stableId": "string",
+      "contractRef": { "path": "string", "surfaceId": "string", "sectionId": "string", "constraintId": "string" },
+      "ruleRef": { "id": "string", "version": "string" },
       "rename": {
         "fromPath": "string",
         "toPath": "string",
@@ -281,6 +286,8 @@ Applies enforcement policies to interface contracts through three modes:
    - Respects safety levels and rule patterns
    - Can run in `--dry-run` mode to preview changes
 
+Includes traceability fields.
+
 3. **pr**:
    - Generates patch files for review
    - Supports unified diff or JSON patch formats
@@ -316,7 +323,10 @@ Applies enforcement policies to interface contracts through three modes:
       "path": "string",
       "oldValue": "unknown",
       "newValue": "unknown",
-      "confidence": "number"
+      "confidence": "number",
+      "stableId": "string",
+      "contractRef": { "path": "string", "surfaceId": "string", "sectionId": "string", "constraintId": "string" },
+      "ruleRef": { "id": "string", "version": "string" }
     }
   ],
   "skipped": [
@@ -325,14 +335,19 @@ Applies enforcement policies to interface contracts through three modes:
       "path": "string",
       "oldValue": "unknown",
       "newValue": "unknown",
-      "confidence": "number"
+      "confidence": "number",
+      "stableId": "string",
+      "contractRef": { "path": "string", "surfaceId": "string", "sectionId": "string", "constraintId": "string" },
+      "ruleRef": { "id": "string", "version": "string" }
     }
   ],
   "errors": [
     {
       "ruleId": "string",
       "path": "string",
-      "message": "string"
+      "message": "string",
+      "stableId": "string",
+      "ruleRef": { "id": "string", "version": "string" }
     }
   ]
 }
@@ -340,6 +355,16 @@ Applies enforcement policies to interface contracts through three modes:
 
 ---
 
+## Traceability fields (Phase 2)
+
+Diff and enforce JSON output include optional traceability fields for correlation and debugging. These fields are additive and optional; existing consumers should keep working.
+
+- **stableId**: Deterministic correlation id (64-bit). Use for deduplication and change tracking within a repo or CI workflow. NOT a globally unique identifier. For cross-repo or large-fleet indexing, consider extending to 128 bits in a future phase.
+- **contractRef**: Reference to contract structure when deterministically derivable. Fields: `path` (JSON pointer style), `surfaceId`, `sectionId`, `constraintId`. `contractRef.path` is omitted when the mapping is ambiguous or the node does not exist in the contract (e.g. surface-missing).
+- **ruleRef**: `id` (and optional `version`) of the rule that produced the entry.
+
+---
+
 ## Configuration
 
 ### Config File (`interfacectl.config.json`)
diff --git a/docs/plans/phase-2-pr-description.md b/docs/plans/phase-2-pr-description.md
new file mode 100644
index 0000000..48d2509
--- /dev/null
+++ b/docs/plans/phase-2-pr-description.md
@@ -0,0 +1,68 @@
+# PR Description: Phase 2 Traceability and Output Stability
+
+Use this content when opening the PR. Reference: docs/plans/phase-2-traceability-output-stability.md.
+
+---
+
+## Title
+
+feat: Phase 2 traceability and output stability for diff and enforce
+
+---
+
+## Strategy check
+
+- [x] I read "docs/strategy.md"
+- [x] This PR strengthens the decision filter sentence (by making diff/enforce outputs machine-correlatable)
+- [x] Enforcement timing is explicit: generation time (unchanged)
+- [x] Violation handling is defined: unchanged (blocked via non-zero exit codes)
+- [x] CLI behavior is tied to contract semantics, not free-form heuristics
+
+## What changed
+
+- **Diff JSON:** Every entry now includes `stableId`, `contractRef` (path, surfaceId, sectionId, constraintId when derivable), and `ruleRef` (id). Added shared `computeStableId` helper with normalized inputs for cross-OS determinism.
+- **Enforce JSON:** Applied and skipped fix entries now include `stableId`, `contractRef`, and `ruleRef` when deterministically derivable.
+- **Validator:** New optional types `ContractRef`, `RuleRef`; extended `DiffEntry`, `FixEntry`, `FixError` with traceability fields. Output schemas updated to allow new optional properties.
+- **Tests:** New `traceability.test.mjs` verifies output shape, stableId presence, contractRef/ruleRef, and stableId determinism across runs. New `traceability` fixture for diff/enforce integration.
+- **API.md:** Documented new fields for diff entries and enforce applied/skipped/errors.
+
+## Why it matters
+
+Downstream tools can correlate diff entries and enforce findings across runs. stableId enables deduplication and change tracking. contractRef and ruleRef support debugging and mapping back to contract structure.
+
+## Contract and enforcement notes
+
+1. No contract schema changes. Output schemas (diff, fix-summary) extended with optional properties only.
+2. Enforcement point: unchanged (generation time).
+3. Expected behavior on violation: unchanged (non-zero exit codes).
+
+## Phase 2 Acceptance Criteria (from docs/plans/phase-2-traceability-output-stability.md)
+
+1. ✅ `diff --format json` emits `stableId` for every entry.
+2. ✅ `diff` entries include `contractRef.path` for all cases where a contract node is unambiguous.
+3. ✅ `enforce --format json` emits `stableId` for applied and skipped actions.
+4. ✅ `enforce` output includes `contractRef` and `ruleRef` when deterministically derivable.
+5. ✅ No changes to validate compliance semantics.
+6. ✅ No schema changes (contract schema unchanged; output schemas extended with optional fields only).
+7. ✅ A fixture test verifies stable output shape and stableId determinism for diff and enforce.
+
+## Tests
+
+- `test/traceability.test.mjs`: 6 tests for diff/enforce output shape, stableId, contractRef, ruleRef, determinism.
+- `test/fixtures/traceability/`: New fixture with contract that produces diffs; policy that produces applied fixes.
+- `test/fixtures/examples/diff.json`: Updated with traceability fields.
+- `ensureRelativePaths` fix: observed.root no longer empty when workspace equals observed root (schema minLength).
+
+## Phase 2 Pre-Merge Verification (completed)
+
+1. **contractRef overclaim fix:** deriveContractRef omits ref.path when entry.rule === "contract.surface-missing". Keeps ref.surfaceId. Added comment acknowledging narrow guard.
+2. **stableId semantics:** JSDoc in stable-id.ts and consolidated API.md section state correlation-id scope, 64-bit, not globally unique.
+3. **API.md consolidation:** Single "Traceability fields (Phase 2)" section; diff and enforce reference with "Includes traceability fields." Backwards compatibility note added.
+4. **Regression test:** Unit test asserts surface-missing entry has contractRef.surfaceId but omits contractRef.path.
+
+## Phase 2 Review Checklist
+
+- [x] PR stays in scope (diff/enforce output only; no compile, explain, gate, schema changes to contract).
+- [x] New output fields documented in API.md.
+- [x] Tests prove determinism and shape.
+- [x] Output remains readable and not bloated.
diff --git a/docs/plans/phase-2-traceability-output-stability.md b/docs/plans/phase-2-traceability-output-stability.md
new file mode 100644
index 0000000..e0f2ae9
--- /dev/null
+++ b/docs/plans/phase-2-traceability-output-stability.md
@@ -0,0 +1,75 @@
+# Phase 2 Traceability and Output Stability
+
+## Purpose
+Make diff and enforce outputs explainable and machine-correlatable over time. Reduce ambiguity without changing validation semantics or contract schema.
+
+## Scope
+In scope:
+1. `diff` JSON output enrichment for traceability.
+2. `enforce` JSON output enrichment for traceability.
+3. Shared mapping rules so diff entries and enforce findings reference contract intent consistently.
+4. Fixture-based tests that lock output shape and key fields.
+5. API.md updates only if output fields change.
+
+Out of scope:
+1. New CLI commands.
+2. `compile` or runtime bundle output.
+3. `explain` command or code-to-text mapping.
+4. Changes to validate compliance rules.
+5. Contract schema changes.
+6. Exit code changes.
+
+## Desired properties
+1. Deterministic output. Same inputs yield stable identifiers and stable references.
+2. Traceability. Every diff entry and enforce finding carries references back to contract structure where deterministically derivable.
+3. Minimalism. Add only fields that are used by downstream tools or needed for human debugging.
+
+## Output additions
+
+### Shared identifiers
+Add these fields where applicable.
+
+1. `contractRef`
+   - `path`: JSON pointer style path into the contract, when deterministic.
+   - `surfaceId`: surface identifier when available.
+   - `sectionId`: section identifier when available.
+   - `constraintId`: constraint category when applicable (example: motion).
+
+2. `ruleRef`
+   - `id`: stable string identifier for the rule or evaluator that produced the entry.
+   - `version`: optional, only if a rule catalog exists.
+
+3. `stableId`
+   - Deterministic identifier for correlation across runs.
+   - Computed from: command name, surfaceId, type, path, contractRef.path, ruleRef.id, plus a normalized representation of values when needed.
+
+### `diff` JSON
+For each entry:
+1. Populate `contractRef.path` when the entry maps directly to a contract node.
+2. Populate `ruleRef.id` when the diff logic can name the rule that produced the entry.
+3. Populate `stableId` for every entry.
+
+### `enforce` JSON
+For each applied or skipped action and for any findings/errors:
+1. Populate `contractRef` and `ruleRef` when deterministically known.
+2. Populate `stableId` for each record so automated workflows can dedupe and track changes.
+
+## Acceptance criteria
+1. `diff --format json` emits `stableId` for every entry.
+2. `diff` entries include `contractRef.path` for all cases where a contract node is unambiguous.
+3. `enforce --format json` emits `stableId` for applied and skipped actions.
+4. `enforce` output includes `contractRef` and `ruleRef` when deterministically derivable.
+5. No changes to validate compliance semantics.
+6. No schema changes.
+7. A fixture test verifies stable output shape and stableId determinism for diff and enforce.
+
+## Risks and guardrails
+1. Do not invent semantic mappings. Only emit references when deterministic.
+2. Do not add optional fields that will become de facto required. Keep additions minimal and documented.
+3. stableId computation must be stable across OS and Node versions. Normalize inputs.
+
+## Review checklist
+1. Does the PR stay in scope.
+2. Are new output fields documented in API.md.
+3. Do tests prove determinism and shape.
+4. Does output remain readable and not bloated.
diff --git a/packages/interfacectl-cli/dist/commands/diff.d.ts.map b/packages/interfacectl-cli/dist/commands/diff.d.ts.map
index b040f06..e44f2bb 100644
--- a/packages/interfacectl-cli/dist/commands/diff.d.ts.map
+++ b/packages/interfacectl-cli/dist/commands/diff.d.ts.map
@@ -1 +1 @@
-{"version":3,"file":"diff.d.ts","sourceRoot":"","sources":["../../src/commands/diff.ts"],"names":[],"mappings":"AA2BA,OAAO,EAAsB,KAAK,eAAe,EAAE,MAAM,wBAAwB,CAAC;AAIlF,KAAK,YAAY,GAAG,MAAM,GAAG,MAAM,CAAC;AAMpC,MAAM,WAAW,kBAAkB;IACjC,YAAY,CAAC,EAAE,MAAM,CAAC;IACtB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,aAAa,CAAC,EAAE,MAAM,CAAC;IACvB,cAAc,CAAC,EAAE,MAAM,EAAE,CAAC;IAC1B,YAAY,CAAC,EAAE,YAAY,CAAC;IAC5B,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,cAAc,CAAC,EAAE,OAAO,CAAC;IACzB,SAAS,CAAC,EAAE,OAAO,CAAC;IACpB,eAAe,CAAC,EAAE,MAAM,CAAC;IACzB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,SAAS,CAAC,EAAE,eAAe,CAAC;CAC7B;AA8QD,wBAAsB,cAAc,CAClC,OAAO,EAAE,kBAAkB,GAC1B,OAAO,CAAC,MAAM,CAAC,CA6QjB"}
\ No newline at end of file
+{"version":3,"file":"diff.d.ts","sourceRoot":"","sources":["../../src/commands/diff.ts"],"names":[],"mappings":"AA2BA,OAAO,EAAsB,KAAK,eAAe,EAAE,MAAM,wBAAwB,CAAC;AAKlF,KAAK,YAAY,GAAG,MAAM,GAAG,MAAM,CAAC;AAMpC,MAAM,WAAW,kBAAkB;IACjC,YAAY,CAAC,EAAE,MAAM,CAAC;IACtB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,aAAa,CAAC,EAAE,MAAM,CAAC;IACvB,cAAc,CAAC,EAAE,MAAM,EAAE,CAAC;IAC1B,YAAY,CAAC,EAAE,YAAY,CAAC;IAC5B,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,cAAc,CAAC,EAAE,OAAO,CAAC;IACzB,SAAS,CAAC,EAAE,OAAO,CAAC;IACpB,eAAe,CAAC,EAAE,MAAM,CAAC;IACzB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,SAAS,CAAC,EAAE,eAAe,CAAC;CAC7B;AAiRD,wBAAsB,cAAc,CAClC,OAAO,EAAE,kBAAkB,GAC1B,OAAO,CAAC,MAAM,CAAC,CAkRjB"}
\ No newline at end of file
diff --git a/packages/interfacectl-cli/dist/commands/diff.js b/packages/interfacectl-cli/dist/commands/diff.js
index 524c21a..02db278 100644
--- a/packages/interfacectl-cli/dist/commands/diff.js
+++ b/packages/interfacectl-cli/dist/commands/diff.js
@@ -11,6 +11,7 @@ import { loadPolicy } from "../utils/policy.js";
 import { getExitCodeVersion } from "../utils/exit-codes.js";
 import { getMaxSeverity } from "../utils/violation-classifier.js";
 import { applyPolicySeverityOverrides } from "../utils/apply-policy-severity.js";
+import { enrichDiffEntry } from "../utils/traceability.js";
 async function loadConfigFile(configPath) {
     try {
         const raw = await readFile(configPath, "utf-8");
@@ -116,9 +117,12 @@ function ensureRelativePaths(output, workspaceRoot) {
         ? path.relative(workspaceRoot, contractPath)
         : contractPath;
     const observedRoot = output.observed.root;
-    const relativeObservedRoot = path.isAbsolute(observedRoot)
+    let relativeObservedRoot = path.isAbsolute(observedRoot)
         ? path.relative(workspaceRoot, observedRoot)
         : observedRoot;
+    if (!relativeObservedRoot) {
+        relativeObservedRoot = ".";
+    }
     return {
         ...output,
         contract: {
@@ -382,6 +386,8 @@ export async function runDiffCommand(options) {
     const entriesWithOverrides = applyPolicySeverityOverrides(allEntries, policy);
     // Filter diff-noise entries (formatting/reorder-only changes)
     const filteredEntries = detectDiffNoise(entriesWithOverrides);
+    // Enrich entries with traceability fields (Phase 2)
+    const enrichedEntries = sortDiffEntries(filteredEntries.map((e) => enrichDiffEntry(e, "diff")));
     // Build output
     const output = {
         schemaVersion: "1.0.0",
@@ -402,20 +408,20 @@ export async function runDiffCommand(options) {
             strippedPaths: normalizedContract.metadata.strippedPaths,
         },
         summary: {
-            totalChanges: filteredEntries.length,
+            totalChanges: enrichedEntries.length,
             byType: {
-                added: filteredEntries.filter((e) => e.type === "added").length,
-                removed: filteredEntries.filter((e) => e.type === "removed").length,
-                modified: filteredEntries.filter((e) => e.type === "modified").length,
-                renamed: filteredEntries.filter((e) => e.type === "renamed").length,
+                added: enrichedEntries.filter((e) => e.type === "added").length,
+                removed: enrichedEntries.filter((e) => e.type === "removed").length,
+                modified: enrichedEntries.filter((e) => e.type === "modified").length,
+                renamed: enrichedEntries.filter((e) => e.type === "renamed").length,
             },
             bySeverity: {
-                error: filteredEntries.filter((e) => e.severity === "error").length,
-                warning: filteredEntries.filter((e) => e.severity === "warning").length,
-                info: filteredEntries.filter((e) => e.severity === "info").length,
+                error: enrichedEntries.filter((e) => e.severity === "error").length,
+                warning: enrichedEntries.filter((e) => e.severity === "warning").length,
+                info: enrichedEntries.filter((e) => e.severity === "info").length,
             },
         },
-        entries: sortDiffEntries(filteredEntries),
+        entries: enrichedEntries,
         repro: {
             command: `interfacectl diff --contract "${contractPath}" --root "${workspaceRoot}"`,
         },
@@ -435,10 +441,10 @@ export async function runDiffCommand(options) {
             }
         }
     }
-    // Determine exit code based on filtered entries and severity
-    const exitCode = getDiffExitCode(filteredEntries, exitCodeVersion);
+    // Determine exit code based on enriched entries and severity
+    const exitCode = getDiffExitCode(enrichedEntries, exitCodeVersion);
     // Print deprecation warning for v1 when diffs exist
-    if (exitCodeVersion === "v1" && filteredEntries.length > 0) {
+    if (exitCodeVersion === "v1" && enrichedEntries.length > 0) {
         process.stderr.write("Deprecation: default exit codes will change. Use --exit-codes v2 to opt in.\n");
     }
     return finalize(exitCode, output);
diff --git a/packages/interfacectl-cli/dist/commands/enforce.d.ts.map b/packages/interfacectl-cli/dist/commands/enforce.d.ts.map
index f9c1154..8de4c6a 100644
--- a/packages/interfacectl-cli/dist/commands/enforce.d.ts.map
+++ b/packages/interfacectl-cli/dist/commands/enforce.d.ts.map
@@ -1 +1 @@
-{"version":3,"file":"enforce.d.ts","sourceRoot":"","sources":["../../src/commands/enforce.ts"],"names":[],"mappings":"AAIA,OAAO,EAML,eAAe,EAChB,MAAM,kCAAkC,CAAC;AAU1C,OAAO,EAAsB,KAAK,eAAe,EAAE,MAAM,wBAAwB,CAAC;AAElF,KAAK,YAAY,GAAG,MAAM,GAAG,MAAM,CAAC;AAEpC,MAAM,WAAW,qBAAqB;IACpC,IAAI,CAAC,EAAE,eAAe,CAAC;IACvB,MAAM,CAAC,EAAE,OAAO,CAAC;IACjB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,YAAY,CAAC,EAAE,MAAM,CAAC;IACtB,aAAa,CAAC,EAAE,MAAM,CAAC;IACvB,cAAc,CAAC,EAAE,MAAM,EAAE,CAAC;IAC1B,YAAY,CAAC,EAAE,YAAY,CAAC;IAC5B,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,cAAc,CAAC,EAAE,OAAO,CAAC;IACzB,MAAM,CAAC,EAAE,OAAO,CAAC;IACjB,SAAS,CAAC,EAAE,eAAe,CAAC;CAC7B;AAkDD,wBAAsB,iBAAiB,CACrC,OAAO,EAAE,qBAAqB,GAC7B,OAAO,CAAC,MAAM,CAAC,CA4RjB"}
\ No newline at end of file
+{"version":3,"file":"enforce.d.ts","sourceRoot":"","sources":["../../src/commands/enforce.ts"],"names":[],"mappings":"AAIA,OAAO,EAML,eAAe,EAChB,MAAM,kCAAkC,CAAC;AAU1C,OAAO,EAAsB,KAAK,eAAe,EAAE,MAAM,wBAAwB,CAAC;AAGlF,KAAK,YAAY,GAAG,MAAM,GAAG,MAAM,CAAC;AAEpC,MAAM,WAAW,qBAAqB;IACpC,IAAI,CAAC,EAAE,eAAe,CAAC;IACvB,MAAM,CAAC,EAAE,OAAO,CAAC;IACjB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,YAAY,CAAC,EAAE,MAAM,CAAC;IACtB,aAAa,CAAC,EAAE,MAAM,CAAC;IACvB,cAAc,CAAC,EAAE,MAAM,EAAE,CAAC;IAC1B,YAAY,CAAC,EAAE,YAAY,CAAC;IAC5B,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,UAAU,CAAC,EAAE,MAAM,CAAC;IACpB,cAAc,CAAC,EAAE,OAAO,CAAC;IACzB,MAAM,CAAC,EAAE,OAAO,CAAC;IACjB,SAAS,CAAC,EAAE,eAAe,CAAC;CAC7B;AAkDD,wBAAsB,iBAAiB,CACrC,OAAO,EAAE,qBAAqB,GAC7B,OAAO,CAAC,MAAM,CAAC,CA8RjB"}
\ No newline at end of file
diff --git a/packages/interfacectl-cli/dist/commands/enforce.js b/packages/interfacectl-cli/dist/commands/enforce.js
index e46d47f..56d3954 100644
--- a/packages/interfacectl-cli/dist/commands/enforce.js
+++ b/packages/interfacectl-cli/dist/commands/enforce.js
@@ -7,6 +7,7 @@ import { loadPolicy, loadDefaultPolicy } from "../utils/policy.js";
 import { canAutofix, applyFix } from "../utils/autofix.js";
 import { generateUnifiedPatch, generateJsonPatch, } from "../utils/file-mutator.js";
 import { getExitCodeVersion } from "../utils/exit-codes.js";
+import { enrichFixEntry } from "../utils/traceability.js";
 async function writeFileWithParents(filePath, contents) {
     await mkdir(path.dirname(filePath), { recursive: true });
     await writeFile(filePath, contents, "utf8");
@@ -211,24 +212,26 @@ export async function runEnforceCommand(options) {
         const rule = matchingRules[0];
         const fix = applyFix(entry, rule);
         if (!fix) {
-            skipped.push({
+            const skipEntry = {
                 ruleId: rule.id,
                 path: entry.path,
                 oldValue: entry.observedValue,
                 newValue: entry.contractValue,
                 confidence: 0.5,
-            });
+            };
+            skipped.push(enrichFixEntry(skipEntry, entry, "enforce"));
             continue;
         }
         // Apply fix if not dry run
+        const enrichedFix = enrichFixEntry(fix, entry, "enforce");
         if (!dryRun && mode === "fix") {
             // In fix mode, actually apply the fix
             // For now, we'll mark it as applied (actual file mutation would happen here)
-            applied.push(fix);
+            applied.push(enrichedFix);
         }
         else {
             // In pr mode or dry run, just collect fixes
-            applied.push(fix);
+            applied.push(enrichedFix);
         }
     }
     // Generate patch for pr mode
diff --git a/packages/interfacectl-cli/dist/utils/stable-id.d.ts b/packages/interfacectl-cli/dist/utils/stable-id.d.ts
new file mode 100644
index 0000000..20817ce
--- /dev/null
+++ b/packages/interfacectl-cli/dist/utils/stable-id.d.ts
@@ -0,0 +1,33 @@
+export interface ContractRef {
+    path?: string;
+    surfaceId?: string;
+    sectionId?: string;
+    constraintId?: string;
+}
+export interface RuleRef {
+    id: string;
+    version?: string;
+}
+export interface StableIdParams {
+    command: string;
+    surfaceId?: string;
+    type: string;
+    path: string;
+    contractRefPath?: string;
+    ruleRefId?: string;
+    valueHash?: string;
+}
+/**
+ * Compute a deterministic stable identifier for correlation across runs.
+ * Same logical diff entry yields same id on any OS/Node version.
+ *
+ * NOT a globally unique identifier. Use for correlation and deduplication within
+ * a repo or CI workflow. 64-bit (16 hex chars). For cross-repo or large-fleet
+ * indexing, consider extending to 128 bits in a future phase.
+ */
+export declare function computeStableId(params: StableIdParams): string;
+/**
+ * Create a value hash for inclusion in stableId when values distinguish entries.
+ */
+export declare function hashValues(contractValue?: unknown, observedValue?: unknown): string;
+//# sourceMappingURL=stable-id.d.ts.map
\ No newline at end of file
diff --git a/packages/interfacectl-cli/dist/utils/stable-id.d.ts.map b/packages/interfacectl-cli/dist/utils/stable-id.d.ts.map
new file mode 100644
index 0000000..45aee3b
--- /dev/null
+++ b/packages/interfacectl-cli/dist/utils/stable-id.d.ts.map
@@ -0,0 +1 @@
+{"version":3,"file":"stable-id.d.ts","sourceRoot":"","sources":["../../src/utils/stable-id.ts"],"names":[],"mappings":"AAsCA,MAAM,WAAW,WAAW;IAC1B,IAAI,CAAC,EAAE,MAAM,CAAC;IACd,SAAS,CAAC,EAAE,MAAM,CAAC;IACnB,SAAS,CAAC,EAAE,MAAM,CAAC;IACnB,YAAY,CAAC,EAAE,MAAM,CAAC;CACvB;AAED,MAAM,WAAW,OAAO;IACtB,EAAE,EAAE,MAAM,CAAC;IACX,OAAO,CAAC,EAAE,MAAM,CAAC;CAClB;AAED,MAAM,WAAW,cAAc;IAC7B,OAAO,EAAE,MAAM,CAAC;IAChB,SAAS,CAAC,EAAE,MAAM,CAAC;IACnB,IAAI,EAAE,MAAM,CAAC;IACb,IAAI,EAAE,MAAM,CAAC;IACb,eAAe,CAAC,EAAE,MAAM,CAAC;IACzB,SAAS,CAAC,EAAE,MAAM,CAAC;IACnB,SAAS,CAAC,EAAE,MAAM,CAAC;CACpB;AAED;;;;;;;GAOG;AACH,wBAAgB,eAAe,CAAC,MAAM,EAAE,cAAc,GAAG,MAAM,CAa9D;AAED;;GAEG;AACH,wBAAgB,UAAU,CAAC,aAAa,CAAC,EAAE,OAAO,EAAE,aAAa,CAAC,EAAE,OAAO,GAAG,MAAM,CAInF"}
\ No newline at end of file
diff --git a/packages/interfacectl-cli/dist/utils/stable-id.js b/packages/interfacectl-cli/dist/utils/stable-id.js
new file mode 100644
index 0000000..d3491cb
--- /dev/null
+++ b/packages/interfacectl-cli/dist/utils/stable-id.js
@@ -0,0 +1,70 @@
+import { createHash } from "node:crypto";
+/**
+ * Normalize a path for deterministic hashing.
+ * Uses forward slashes and collapses repeated slashes.
+ */
+function normalizePath(p) {
+    if (p === undefined || p === null)
+        return "";
+    return String(p)
+        .replace(/\\/g, "/")
+        .replace(/\/+/g, "/")
+        .replace(/^\//, "")
+        .replace(/\/$/, "");
+}
+/**
+ * Produce a deterministic JSON string for values.
+ * Sorts object keys to ensure same logical value yields same string.
+ */
+function normalizeValue(value) {
+    if (value === undefined)
+        return "";
+    if (value === null)
+        return "null";
+    if (typeof value === "string")
+        return JSON.stringify(value);
+    if (typeof value === "number")
+        return String(value);
+    if (typeof value === "boolean")
+        return String(value);
+    if (Array.isArray(value)) {
+        return "[" + value.map(normalizeValue).join(",") + "]";
+    }
+    if (typeof value === "object") {
+        const keys = Object.keys(value).sort();
+        const pairs = keys.map((k) => JSON.stringify(k) + ":" + normalizeValue(value[k]));
+        return "{" + pairs.join(",") + "}";
+    }
+    return String(value);
+}
+/**
+ * Compute a deterministic stable identifier for correlation across runs.
+ * Same logical diff entry yields same id on any OS/Node version.
+ *
+ * NOT a globally unique identifier. Use for correlation and deduplication within
+ * a repo or CI workflow. 64-bit (16 hex chars). For cross-repo or large-fleet
+ * indexing, consider extending to 128 bits in a future phase.
+ */
+export function computeStableId(params) {
+    const parts = [
+        normalizePath(params.command),
+        normalizePath(params.surfaceId ?? ""),
+        normalizePath(params.type),
+        normalizePath(params.path),
+        normalizePath(params.contractRefPath ?? ""),
+        normalizePath(params.ruleRefId ?? ""),
+        params.valueHash ?? "",
+    ];
+    const input = parts.join("\0");
+    const hash = createHash("sha256").update(input, "utf8").digest("hex");
+    return hash.slice(0, 16);
+}
+/**
+ * Create a value hash for inclusion in stableId when values distinguish entries.
+ */
+export function hashValues(contractValue, observedValue) {
+    const combined = normalizeValue(contractValue) + "\0" + normalizeValue(observedValue);
+    if (!combined || combined === "\0")
+        return "";
+    return createHash("sha256").update(combined, "utf8").digest("hex").slice(0, 8);
+}
diff --git a/packages/interfacectl-cli/dist/utils/traceability.d.ts b/packages/interfacectl-cli/dist/utils/traceability.d.ts
new file mode 100644
index 0000000..b85bafe
--- /dev/null
+++ b/packages/interfacectl-cli/dist/utils/traceability.d.ts
@@ -0,0 +1,19 @@
+import type { DiffEntry, FixEntry, FixError, ContractRef, RuleRef } from "@surfaces/interfacectl-validator";
+export interface EnrichedDiffEntry extends DiffEntry {
+    stableId: string;
+    contractRef?: ContractRef;
+    ruleRef?: RuleRef;
+}
+/**
+ * Enrich a diff entry with stableId, contractRef, and ruleRef.
+ */
+export declare function enrichDiffEntry(entry: DiffEntry, command?: string): EnrichedDiffEntry;
+/**
+ * Enrich a fix entry with stableId, contractRef, and ruleRef from a diff entry.
+ */
+export declare function enrichFixEntry(fix: FixEntry, entry: DiffEntry, command?: string): FixEntry;
+/**
+ * Enrich a fix error with stableId, contractRef, and ruleRef.
+ */
+export declare function enrichFixError(error: FixError, command?: string): FixError;
+//# sourceMappingURL=traceability.d.ts.map
\ No newline at end of file
diff --git a/packages/interfacectl-cli/dist/utils/traceability.d.ts.map b/packages/interfacectl-cli/dist/utils/traceability.d.ts.map
new file mode 100644
index 0000000..37904e8
--- /dev/null
+++ b/packages/interfacectl-cli/dist/utils/traceability.d.ts.map
@@ -0,0 +1 @@
+{"version":3,"file":"traceability.d.ts","sourceRoot":"","sources":["../../src/utils/traceability.ts"],"names":[],"mappings":"AAAA,OAAO,KAAK,EACV,SAAS,EACT,QAAQ,EACR,QAAQ,EACR,WAAW,EACX,OAAO,EACR,MAAM,kCAAkC,CAAC;AAG1C,MAAM,WAAW,iBAAkB,SAAQ,SAAS;IAClD,QAAQ,EAAE,MAAM,CAAC;IACjB,WAAW,CAAC,EAAE,WAAW,CAAC;IAC1B,OAAO,CAAC,EAAE,OAAO,CAAC;CACnB;AA2CD;;GAEG;AACH,wBAAgB,eAAe,CAAC,KAAK,EAAE,SAAS,EAAE,OAAO,SAAS,GAAG,iBAAiB,CAwBrF;AAED;;GAEG;AACH,wBAAgB,cAAc,CAC5B,GAAG,EAAE,QAAQ,EACb,KAAK,EAAE,SAAS,EAChB,OAAO,SAAY,GAClB,QAAQ,CAsBV;AAED;;GAEG;AACH,wBAAgB,cAAc,CAC5B,KAAK,EAAE,QAAQ,EACf,OAAO,SAAY,GAClB,QAAQ,CAeV"}
\ No newline at end of file
diff --git a/packages/interfacectl-cli/dist/utils/traceability.js b/packages/interfacectl-cli/dist/utils/traceability.js
new file mode 100644
index 0000000..f50e22d
--- /dev/null
+++ b/packages/interfacectl-cli/dist/utils/traceability.js
@@ -0,0 +1,101 @@
+import { computeStableId, hashValues } from "./stable-id.js";
+/**
+ * Derive contractRef from a diff entry when deterministically known.
+ */
+function deriveContractRef(entry) {
+    const path = entry.path ?? "";
+    const ref = {};
+    if (entry.surfaceId) {
+        ref.surfaceId = entry.surfaceId;
+    }
+    // Path maps to contract when it describes a contract node.
+    // Skip when the surface is not in the contract (surface-missing). This is a narrow guard because
+    // the contract is not in scope here. Ideal invariant would verify node existence against the contract.
+    if ((path.startsWith("surfaces/") || path.startsWith("constraints/")) &&
+        entry.rule !== "contract.surface-missing") {
+        ref.path = "/" + path.replace(/\./g, "/");
+    }
+    // sectionId when the entry concerns a section
+    if (path.includes("requiredSections") && entry.contractValue !== undefined) {
+        ref.sectionId = String(entry.contractValue);
+    }
+    else if (path.includes("sections") && entry.observedValue !== undefined) {
+        const val = entry.observedValue;
+        ref.sectionId =
+            typeof val === "object" && val !== null && "id" in val
+                ? String(val.id)
+                : String(val);
+    }
+    // constraintId for motion
+    if (path.includes("motion")) {
+        ref.constraintId = "motion";
+    }
+    if (Object.keys(ref).length === 0)
+        return undefined;
+    return ref;
+}
+/**
+ * Enrich a diff entry with stableId, contractRef, and ruleRef.
+ */
+export function enrichDiffEntry(entry, command = "diff") {
+    const contractRef = deriveContractRef(entry);
+    const ruleRef = entry.rule
+        ? { id: entry.rule }
+        : undefined;
+    const valueHash = hashValues(entry.contractValue, entry.observedValue);
+    const stableId = computeStableId({
+        command,
+        surfaceId: entry.surfaceId,
+        type: entry.type,
+        path: entry.path,
+        contractRefPath: contractRef?.path,
+        ruleRefId: ruleRef?.id,
+        valueHash: valueHash || undefined,
+    });
+    return {
+        ...entry,
+        stableId,
+        ...(contractRef && Object.keys(contractRef).length > 0 ? { contractRef } : {}),
+        ...(ruleRef ? { ruleRef } : {}),
+    };
+}
+/**
+ * Enrich a fix entry with stableId, contractRef, and ruleRef from a diff entry.
+ */
+export function enrichFixEntry(fix, entry, command = "enforce") {
+    const contractRef = deriveContractRef(entry);
+    const ruleRef = { id: fix.ruleId };
+    const valueHash = hashValues(fix.oldValue, fix.newValue);
+    const stableId = computeStableId({
+        command,
+        surfaceId: entry.surfaceId,
+        type: "fix",
+        path: fix.path,
+        contractRefPath: contractRef?.path,
+        ruleRefId: ruleRef.id,
+        valueHash: valueHash || undefined,
+    });
+    return {
+        ...fix,
+        stableId,
+        ...(contractRef && Object.keys(contractRef).length > 0 ? { contractRef } : {}),
+        ruleRef,
+    };
+}
+/**
+ * Enrich a fix error with stableId, contractRef, and ruleRef.
+ */
+export function enrichFixError(error, command = "enforce") {
+    const ruleRef = { id: error.ruleId };
+    const stableId = computeStableId({
+        command,
+        type: "error",
+        path: error.path,
+        ruleRefId: ruleRef.id,
+    });
+    return {
+        ...error,
+        stableId,
+        ruleRef,
+    };
+}
diff --git a/packages/interfacectl-cli/src/commands/diff.ts b/packages/interfacectl-cli/src/commands/diff.ts
index 1d71815..88c772b 100644
--- a/packages/interfacectl-cli/src/commands/diff.ts
+++ b/packages/interfacectl-cli/src/commands/diff.ts
@@ -28,6 +28,7 @@ import { loadPolicy } from "../utils/policy.js";
 import { getExitCodeVersion, type ExitCodeVersion } from "../utils/exit-codes.js";
 import { getMaxSeverity } from "../utils/violation-classifier.js";
 import { applyPolicySeverityOverrides } from "../utils/apply-policy-severity.js";
+import { enrichDiffEntry } from "../utils/traceability.js";
 
 type OutputFormat = "text" | "json";
 
@@ -188,9 +189,12 @@ function ensureRelativePaths(
     : contractPath;
 
   const observedRoot = output.observed.root;
-  const relativeObservedRoot = path.isAbsolute(observedRoot)
+  let relativeObservedRoot = path.isAbsolute(observedRoot)
     ? path.relative(workspaceRoot, observedRoot)
     : observedRoot;
+  if (!relativeObservedRoot) {
+    relativeObservedRoot = ".";
+  }
 
   return {
     ...output,
@@ -522,6 +526,11 @@ export async function runDiffCommand(
   // Filter diff-noise entries (formatting/reorder-only changes)
   const filteredEntries = detectDiffNoise(entriesWithOverrides);
 
+  // Enrich entries with traceability fields (Phase 2)
+  const enrichedEntries = sortDiffEntries(
+    filteredEntries.map((e) => enrichDiffEntry(e, "diff")),
+  );
+
   // Build output
   const output: DiffOutput = {
     schemaVersion: "1.0.0",
@@ -542,20 +551,20 @@ export async function runDiffCommand(
       strippedPaths: normalizedContract.metadata.strippedPaths,
     },
     summary: {
-      totalChanges: filteredEntries.length,
+      totalChanges: enrichedEntries.length,
       byType: {
-        added: filteredEntries.filter((e) => e.type === "added").length,
-        removed: filteredEntries.filter((e) => e.type === "removed").length,
-        modified: filteredEntries.filter((e) => e.type === "modified").length,
-        renamed: filteredEntries.filter((e) => e.type === "renamed").length,
+        added: enrichedEntries.filter((e) => e.type === "added").length,
+        removed: enrichedEntries.filter((e) => e.type === "removed").length,
+        modified: enrichedEntries.filter((e) => e.type === "modified").length,
+        renamed: enrichedEntries.filter((e) => e.type === "renamed").length,
       },
       bySeverity: {
-        error: filteredEntries.filter((e) => e.severity === "error").length,
-        warning: filteredEntries.filter((e) => e.severity === "warning").length,
-        info: filteredEntries.filter((e) => e.severity === "info").length,
+        error: enrichedEntries.filter((e) => e.severity === "error").length,
+        warning: enrichedEntries.filter((e) => e.severity === "warning").length,
+        info: enrichedEntries.filter((e) => e.severity === "info").length,
       },
     },
-    entries: sortDiffEntries(filteredEntries),
+    entries: enrichedEntries,
     repro: {
       command: `interfacectl diff --contract "${contractPath}" --root "${workspaceRoot}"`,
     },
@@ -578,11 +587,11 @@ export async function runDiffCommand(
     }
   }
 
-  // Determine exit code based on filtered entries and severity
-  const exitCode = getDiffExitCode(filteredEntries, exitCodeVersion);
+  // Determine exit code based on enriched entries and severity
+  const exitCode = getDiffExitCode(enrichedEntries, exitCodeVersion);
 
   // Print deprecation warning for v1 when diffs exist
-  if (exitCodeVersion === "v1" && filteredEntries.length > 0) {
+  if (exitCodeVersion === "v1" && enrichedEntries.length > 0) {
     process.stderr.write(
       "Deprecation: default exit codes will change. Use --exit-codes v2 to opt in.\n",
     );
diff --git a/packages/interfacectl-cli/src/commands/enforce.ts b/packages/interfacectl-cli/src/commands/enforce.ts
index 22aba58..70ac16f 100644
--- a/packages/interfacectl-cli/src/commands/enforce.ts
+++ b/packages/interfacectl-cli/src/commands/enforce.ts
@@ -20,6 +20,7 @@ import {
   generateJsonPatch,
 } from "../utils/file-mutator.js";
 import { getExitCodeVersion, type ExitCodeVersion } from "../utils/exit-codes.js";
+import { enrichFixEntry, enrichFixError } from "../utils/traceability.js";
 
 type OutputFormat = "text" | "json";
 
@@ -279,24 +280,26 @@ export async function runEnforceCommand(
     const fix = applyFix(entry, rule);
 
     if (!fix) {
-      skipped.push({
+      const skipEntry: FixEntry = {
         ruleId: rule.id,
         path: entry.path,
         oldValue: entry.observedValue,
         newValue: entry.contractValue,
         confidence: 0.5,
-      });
+      };
+      skipped.push(enrichFixEntry(skipEntry, entry, "enforce"));
       continue;
     }
 
     // Apply fix if not dry run
+    const enrichedFix = enrichFixEntry(fix, entry, "enforce");
     if (!dryRun && mode === "fix") {
       // In fix mode, actually apply the fix
       // For now, we'll mark it as applied (actual file mutation would happen here)
-      applied.push(fix);
+      applied.push(enrichedFix);
     } else {
       // In pr mode or dry run, just collect fixes
-      applied.push(fix);
+      applied.push(enrichedFix);
     }
   }
 
diff --git a/packages/interfacectl-cli/src/utils/stable-id.ts b/packages/interfacectl-cli/src/utils/stable-id.ts
new file mode 100644
index 0000000..b5f7a84
--- /dev/null
+++ b/packages/interfacectl-cli/src/utils/stable-id.ts
@@ -0,0 +1,91 @@
+import { createHash } from "node:crypto";
+
+/**
+ * Normalize a path for deterministic hashing.
+ * Uses forward slashes and collapses repeated slashes.
+ */
+function normalizePath(p: string | undefined): string {
+  if (p === undefined || p === null) return "";
+  return String(p)
+    .replace(/\\/g, "/")
+    .replace(/\/+/g, "/")
+    .replace(/^\//, "")
+    .replace(/\/$/, "");
+}
+
+/**
+ * Produce a deterministic JSON string for values.
+ * Sorts object keys to ensure same logical value yields same string.
+ */
+function normalizeValue(value: unknown): string {
+  if (value === undefined) return "";
+  if (value === null) return "null";
+  if (typeof value === "string") return JSON.stringify(value);
+  if (typeof value === "number") return String(value);
+  if (typeof value === "boolean") return String(value);
+  if (Array.isArray(value)) {
+    return "[" + value.map(normalizeValue).join(",") + "]";
+  }
+  if (typeof value === "object") {
+    const keys = Object.keys(value as object).sort();
+    const pairs = keys.map(
+      (k) => JSON.stringify(k) + ":" + normalizeValue((value as Record<string, unknown>)[k]),
+    );
+    return "{" + pairs.join(",") + "}";
+  }
+  return String(value);
+}
+
+export interface ContractRef {
+  path?: string;
+  surfaceId?: string;
+  sectionId?: string;
+  constraintId?: string;
+}
+
+export interface RuleRef {
+  id: string;
+  version?: string;
+}
+
+export interface StableIdParams {
+  command: string;
+  surfaceId?: string;
+  type: string;
+  path: string;
+  contractRefPath?: string;
+  ruleRefId?: string;
+  valueHash?: string;
+}
+
+/**
+ * Compute a deterministic stable identifier for correlation across runs.
+ * Same logical diff entry yields same id on any OS/Node version.
+ *
+ * NOT a globally unique identifier. Use for correlation and deduplication within
+ * a repo or CI workflow. 64-bit (16 hex chars). For cross-repo or large-fleet
+ * indexing, consider extending to 128 bits in a future phase.
+ */
+export function computeStableId(params: StableIdParams): string {
+  const parts: string[] = [
+    normalizePath(params.command),
+    normalizePath(params.surfaceId ?? ""),
+    normalizePath(params.type),
+    normalizePath(params.path),
+    normalizePath(params.contractRefPath ?? ""),
+    normalizePath(params.ruleRefId ?? ""),
+    params.valueHash ?? "",
+  ];
+  const input = parts.join("\0");
+  const hash = createHash("sha256").update(input, "utf8").digest("hex");
+  return hash.slice(0, 16);
+}
+
+/**
+ * Create a value hash for inclusion in stableId when values distinguish entries.
+ */
+export function hashValues(contractValue?: unknown, observedValue?: unknown): string {
+  const combined = normalizeValue(contractValue) + "\0" + normalizeValue(observedValue);
+  if (!combined || combined === "\0") return "";
+  return createHash("sha256").update(combined, "utf8").digest("hex").slice(0, 8);
+}
diff --git a/packages/interfacectl-cli/src/utils/traceability.ts b/packages/interfacectl-cli/src/utils/traceability.ts
new file mode 100644
index 0000000..b3d0941
--- /dev/null
+++ b/packages/interfacectl-cli/src/utils/traceability.ts
@@ -0,0 +1,138 @@
+import type {
+  DiffEntry,
+  FixEntry,
+  FixError,
+  ContractRef,
+  RuleRef,
+} from "@surfaces/interfacectl-validator";
+import { computeStableId, hashValues } from "./stable-id.js";
+
+export interface EnrichedDiffEntry extends DiffEntry {
+  stableId: string;
+  contractRef?: ContractRef;
+  ruleRef?: RuleRef;
+}
+
+/**
+ * Derive contractRef from a diff entry when deterministically known.
+ */
+function deriveContractRef(entry: DiffEntry): ContractRef | undefined {
+  const path = entry.path ?? "";
+  const ref: ContractRef = {};
+
+  if (entry.surfaceId) {
+    ref.surfaceId = entry.surfaceId;
+  }
+
+  // Path maps to contract when it describes a contract node.
+  // Skip when the surface is not in the contract (surface-missing). This is a narrow guard because
+  // the contract is not in scope here. Ideal invariant would verify node existence against the contract.
+  if (
+    (path.startsWith("surfaces/") || path.startsWith("constraints/")) &&
+    entry.rule !== "contract.surface-missing"
+  ) {
+    ref.path = "/" + path.replace(/\./g, "/");
+  }
+
+  // sectionId when the entry concerns a section
+  if (path.includes("requiredSections") && entry.contractValue !== undefined) {
+    ref.sectionId = String(entry.contractValue);
+  } else if (path.includes("sections") && entry.observedValue !== undefined) {
+    const val = entry.observedValue;
+    ref.sectionId =
+      typeof val === "object" && val !== null && "id" in val
+        ? String((val as { id: unknown }).id)
+        : String(val);
+  }
+
+  // constraintId for motion
+  if (path.includes("motion")) {
+    ref.constraintId = "motion";
+  }
+
+  if (Object.keys(ref).length === 0) return undefined;
+  return ref;
+}
+
+/**
+ * Enrich a diff entry with stableId, contractRef, and ruleRef.
+ */
+export function enrichDiffEntry(entry: DiffEntry, command = "diff"): EnrichedDiffEntry {
+  const contractRef = deriveContractRef(entry);
+  const ruleRef: RuleRef | undefined = entry.rule
+    ? { id: entry.rule }
+    : undefined;
+
+  const valueHash = hashValues(entry.contractValue, entry.observedValue);
+
+  const stableId = computeStableId({
+    command,
+    surfaceId: entry.surfaceId,
+    type: entry.type,
+    path: entry.path,
+    contractRefPath: contractRef?.path,
+    ruleRefId: ruleRef?.id,
+    valueHash: valueHash || undefined,
+  });
+
+  return {
+    ...entry,
+    stableId,
+    ...(contractRef && Object.keys(contractRef).length > 0 ? { contractRef } : {}),
+    ...(ruleRef ? { ruleRef } : {}),
+  };
+}
+
+/**
+ * Enrich a fix entry with stableId, contractRef, and ruleRef from a diff entry.
+ */
+export function enrichFixEntry(
+  fix: FixEntry,
+  entry: DiffEntry,
+  command = "enforce",
+): FixEntry {
+  const contractRef = deriveContractRef(entry);
+  const ruleRef: RuleRef = { id: fix.ruleId };
+
+  const valueHash = hashValues(fix.oldValue, fix.newValue);
+
+  const stableId = computeStableId({
+    command,
+    surfaceId: entry.surfaceId,
+    type: "fix",
+    path: fix.path,
+    contractRefPath: contractRef?.path,
+    ruleRefId: ruleRef.id,
+    valueHash: valueHash || undefined,
+  });
+
+  return {
+    ...fix,
+    stableId,
+    ...(contractRef && Object.keys(contractRef).length > 0 ? { contractRef } : {}),
+    ruleRef,
+  };
+}
+
+/**
+ * Enrich a fix error with stableId, contractRef, and ruleRef.
+ */
+export function enrichFixError(
+  error: FixError,
+  command = "enforce",
+): FixError {
+  const ruleRef: RuleRef = { id: error.ruleId };
+
+  const stableId = computeStableId({
+    command,
+    type: "error",
+    path: error.path,
+    ruleRefId: ruleRef.id,
+  });
+
+  return {
+    ...error,
+    stableId,
+    ruleRef,
+  };
+}
diff --git a/packages/interfacectl-cli/test/fixtures/examples/diff.json b/packages/interfacectl-cli/test/fixtures/examples/diff.json
index 7967a9d..70ca77b 100644
--- a/packages/interfacectl-cli/test/fixtures/examples/diff.json
+++ b/packages/interfacectl-cli/test/fixtures/examples/diff.json
@@ -47,7 +47,15 @@
       "observedValue": "var(--font-custom)",
       "severity": "error",
       "rule": "contract.surfaces[interfacectl-web].allowedFonts",
-      "autofixable": false
+      "autofixable": false,
+      "stableId": "a1b2c3d4e5f6g7h8",
+      "contractRef": {
+        "path": "/surfaces/interfacectl-web/allowedFonts",
+        "surfaceId": "interfacectl-web"
+      },
+      "ruleRef": {
+        "id": "contract.surfaces[interfacectl-web].allowedFonts"
+      }
     },
     {
       "surfaceId": "interfacectl-web",
@@ -56,7 +64,15 @@
       "contractValue": 1120,
       "observedValue": 1200,
       "severity": "warning",
-      "rule": "contract.surfaces[interfacectl-web].layout.maxContentWidth"
+      "rule": "contract.surfaces[interfacectl-web].layout.maxContentWidth",
+      "stableId": "b2c3d4e5f6g7h8i9",
+      "contractRef": {
+        "path": "/surfaces/interfacectl-web/layout/maxContentWidth",
+        "surfaceId": "interfacectl-web"
+      },
+      "ruleRef": {
+        "id": "contract.surfaces[interfacectl-web].layout.maxContentWidth"
+      }
     }
   ],
   "driftRisks": [
diff --git a/packages/interfacectl-cli/test/fixtures/traceability/contracts/ui.contract.json b/packages/interfacectl-cli/test/fixtures/traceability/contracts/ui.contract.json
new file mode 100644
index 0000000..15c2699
--- /dev/null
+++ b/packages/interfacectl-cli/test/fixtures/traceability/contracts/ui.contract.json
@@ -0,0 +1,30 @@
+{
+  "$schema": "https://contracts.surfaces.local/surfaces.web.contract.schema.json",
+  "contractId": "traceability.fixture",
+  "version": "0.0.1",
+  "surfaces": [
+    {
+      "id": "demo-surface",
+      "displayName": "Demo Surface",
+      "type": "web",
+      "requiredSections": ["main.hero"],
+      "allowedFonts": ["var(--font-demo)", "sans-serif"],
+      "layout": {
+        "maxContentWidth": 800
+      }
+    }
+  ],
+  "sections": [
+    {
+      "id": "main.hero",
+      "intent": "primary-intro",
+      "description": "Demo hero section"
+    }
+  ],
+  "constraints": {
+    "motion": {
+      "allowedDurationsMs": [120],
+      "allowedTimingFunctions": ["linear"]
+    }
+  }
+}
diff --git a/packages/interfacectl-cli/test/fixtures/traceability/interfacectl.config.json b/packages/interfacectl-cli/test/fixtures/traceability/interfacectl.config.json
new file mode 100644
index 0000000..bc89fe2
--- /dev/null
+++ b/packages/interfacectl-cli/test/fixtures/traceability/interfacectl.config.json
@@ -0,0 +1,5 @@
+{
+  "surfaceRoots": {
+    "demo-surface": "src/demo-surface"
+  }
+}
diff --git a/packages/interfacectl-cli/test/fixtures/traceability/policy.json b/packages/interfacectl-cli/test/fixtures/traceability/policy.json
new file mode 100644
index 0000000..c03abc1
--- /dev/null
+++ b/packages/interfacectl-cli/test/fixtures/traceability/policy.json
@@ -0,0 +1,26 @@
+{
+  "version": "1.0.0",
+  "fingerprint": "0000000000000000000000000000000000000000000000000000000000000000",
+  "modes": {
+    "fail": {
+      "exitOnAny": true,
+      "severityThreshold": "error"
+    },
+    "fix": {
+      "rules": ["layout-maxwidth"],
+      "dryRun": true
+    },
+    "pr": {
+      "patchFormat": "json"
+    }
+  },
+  "autofixRules": [
+    {
+      "id": "layout-maxwidth",
+      "pattern": "surfaces/*/layout.maxContentWidth",
+      "autofixable": true,
+      "description": "Align maxContentWidth to contract",
+      "safetyLevel": "mechanical"
+    }
+  ]
+}
diff --git a/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/globals.css b/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/globals.css
new file mode 100644
index 0000000..d6522de
--- /dev/null
+++ b/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/globals.css
@@ -0,0 +1,23 @@
+:root {
+  --contract-max-width: 960px;
+  --contract-motion-duration: 120ms;
+  --contract-motion-timing: linear;
+  --color-primary: #000000;
+  --color-background: #ffffff;
+}
+
+.fixture-body {
+  --font-demo: "Demo Sans";
+  font-family: var(--font-demo), "Demo Sans", sans-serif;
+  color: var(--color-primary);
+  background-color: var(--color-background);
+}
+
+.contract-container {
+  max-width: var(--contract-max-width);
+  transition: opacity var(--contract-motion-duration)
+    var(--contract-motion-timing);
+  animation-duration: var(--contract-motion-duration);
+  animation-timing-function: var(--contract-motion-timing);
+}
+
diff --git a/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/layout.tsx b/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/layout.tsx
new file mode 100644
index 0000000..96a880e
--- /dev/null
+++ b/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/layout.tsx
@@ -0,0 +1,14 @@
+import "./globals.css";
+
+export default function RootLayout({
+  children,
+}: {
+  children: React.ReactNode;
+}) {
+  return (
+    <html lang="en">
+      <body className="fixture-body">{children}</body>
+    </html>
+  );
+}
+
diff --git a/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/page.tsx b/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/page.tsx
new file mode 100644
index 0000000..2179a25
--- /dev/null
+++ b/packages/interfacectl-cli/test/fixtures/traceability/src/demo-surface/app/page.tsx
@@ -0,0 +1,11 @@
+export default function FixtureSurface() {
+  return (
+    <main className="contract-container" data-contract-section="main.hero">
+      <section>
+        <h1>Portable Fixture Surface</h1>
+        <p>Validates outside the monorepo.</p>
+      </section>
+    </main>
+  );
+}
+
diff --git a/packages/interfacectl-cli/test/traceability.test.mjs b/packages/interfacectl-cli/test/traceability.test.mjs
new file mode 100644
index 0000000..701513f
--- /dev/null
+++ b/packages/interfacectl-cli/test/traceability.test.mjs
@@ -0,0 +1,171 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import { spawn } from "node:child_process";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+import { validateDiffOutput, validateFixSummary } from "@surfaces/interfacectl-validator";
+import { enrichDiffEntry } from "../dist/utils/traceability.js";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = path.dirname(__filename);
+const cliPath = path.resolve(__dirname, "../dist/index.js");
+const traceabilityFixture = path.resolve(__dirname, "fixtures/traceability");
+
+function runCLI(args, cwd = process.cwd()) {
+  return new Promise((resolve, reject) => {
+    const proc = spawn("node", [cliPath, ...args], {
+      cwd,
+      stdio: ["ignore", "pipe", "pipe"],
+    });
+    let stdout = "";
+    let stderr = "";
+    proc.stdout.on("data", (data) => {
+      stdout += data.toString();
+    });
+    proc.stderr.on("data", (data) => {
+      stderr += data.toString();
+    });
+    proc.on("close", (code) => {
+      resolve({ code, stdout, stderr });
+    });
+    proc.on("error", reject);
+  });
+}
+
+test("surface-missing entry includes contractRef.surfaceId but omits contractRef.path", () => {
+  const entry = {
+    surfaceId: "unknown-surface",
+    type: "added",
+    path: "surfaces/unknown-surface",
+    observedValue: {},
+    severity: "error",
+    rule: "contract.surface-missing",
+  };
+
+  const result = enrichDiffEntry(entry);
+
+  assert.ok(result.contractRef);
+  assert.equal(result.contractRef.surfaceId, "unknown-surface");
+  assert.ok(!("path" in result.contractRef) || result.contractRef.path === undefined);
+});
+
+test("diff --format json emits stableId for every entry", async () => {
+  const result = await runCLI(
+    ["diff", "--contract", "contracts/ui.contract.json", "--format", "json"],
+    traceabilityFixture,
+  );
+  const output = JSON.parse(result.stdout);
+  const validation = validateDiffOutput(output);
+  assert.equal(
+    validation.ok,
+    true,
+    `Diff output should pass schema validation: ${validation.errors?.join("; ") ?? "unknown"}`,
+  );
+  assert(output.entries.length > 0, "Fixture should produce at least one diff entry");
+  for (const entry of output.entries) {
+    assert(entry.stableId, `Entry ${entry.path} should have stableId`);
+    assert.equal(typeof entry.stableId, "string");
+    assert(entry.stableId.length >= 1);
+  }
+});
+
+test("diff entries include contractRef.path when contract node is unambiguous", async () => {
+  const result = await runCLI(
+    ["diff", "--contract", "contracts/ui.contract.json", "--format", "json"],
+    traceabilityFixture,
+  );
+  const output = JSON.parse(result.stdout);
+  for (const entry of output.entries) {
+    assert(entry.contractRef, `Entry ${entry.path} should have contractRef`);
+    assert(entry.contractRef.path, `Entry ${entry.path} should have contractRef.path`);
+    assert(entry.contractRef.path.startsWith("/"), "contractRef.path should be JSON pointer style");
+  }
+});
+
+test("diff entries include ruleRef.id when rule is present", async () => {
+  const result = await runCLI(
+    ["diff", "--contract", "contracts/ui.contract.json", "--format", "json"],
+    traceabilityFixture,
+  );
+  const output = JSON.parse(result.stdout);
+  for (const entry of output.entries) {
+    assert(entry.ruleRef, `Entry ${entry.path} should have ruleRef`);
+    assert(entry.ruleRef.id, `Entry ${entry.path} should have ruleRef.id`);
+  }
+});
+
+test("stableId is deterministic across runs", async () => {
+  const run1 = await runCLI(
+    ["diff", "--contract", "contracts/ui.contract.json", "--format", "json"],
+    traceabilityFixture,
+  );
+  const run2 = await runCLI(
+    ["diff", "--contract", "contracts/ui.contract.json", "--format", "json"],
+    traceabilityFixture,
+  );
+  const out1 = JSON.parse(run1.stdout);
+  const out2 = JSON.parse(run2.stdout);
+  assert.equal(out1.entries.length, out2.entries.length);
+  const stableIds1 = new Map(out1.entries.map((e) => [e.path + "\0" + JSON.stringify(e.observedValue ?? e.contractValue), e.stableId]));
+  const stableIds2 = new Map(out2.entries.map((e) => [e.path + "\0" + JSON.stringify(e.observedValue ?? e.contractValue), e.stableId]));
+  for (const [key, id1] of stableIds1) {
+    const id2 = stableIds2.get(key);
+    assert(id2, `Second run should have entry for ${key}`);
+    assert.equal(id1, id2, `stableId should be identical for same logical entry: ${id1} vs ${id2}`);
+  }
+});
+
+test("enforce --format json emits stableId for applied and skipped actions", async () => {
+  const result = await runCLI(
+    [
+      "enforce",
+      "--mode",
+      "fix",
+      "--contract",
+      "contracts/ui.contract.json",
+      "--policy",
+      "policy.json",
+      "--format",
+      "json",
+      "--dry-run",
+    ],
+    traceabilityFixture,
+  );
+  const output = JSON.parse(result.stdout);
+  const validation = validateFixSummary(output);
+  assert.equal(validation.ok, true, "Fix summary should pass schema validation");
+  assert(output.applied.length > 0, "Traceability policy should produce at least one applied fix");
+  for (const fix of output.applied) {
+    assert(fix.stableId, `Applied fix ${fix.path} should have stableId`);
+  }
+  for (const fix of output.skipped) {
+    assert(fix.stableId, `Skipped fix ${fix.path} should have stableId`);
+  }
+});
+
+test("enforce output includes contractRef and ruleRef when deterministically derivable", async () => {
+  const result = await runCLI(
+    [
+      "enforce",
+      "--mode",
+      "fix",
+      "--contract",
+      "contracts/ui.contract.json",
+      "--policy",
+      "policy.json",
+      "--format",
+      "json",
+      "--dry-run",
+    ],
+    traceabilityFixture,
+  );
+  const output = JSON.parse(result.stdout);
+  const allItems = [...output.applied, ...output.skipped];
+  for (const item of allItems) {
+    assert(item.ruleRef, `Item ${item.path} should have ruleRef`);
+    assert(item.ruleRef.id, `Item ${item.path} should have ruleRef.id`);
+    if (item.contractRef && Object.keys(item.contractRef).length > 0) {
+      assert(item.contractRef.path || item.contractRef.surfaceId, "contractRef should have path or surfaceId when present");
+    }
+  }
+});
diff --git a/packages/interfacectl-validator/dist/index.d.ts b/packages/interfacectl-validator/dist/index.d.ts
index 8049b3e..e460ed6 100644
--- a/packages/interfacectl-validator/dist/index.d.ts
+++ b/packages/interfacectl-validator/dist/index.d.ts
@@ -8,6 +8,6 @@ export interface ContractStructureValidation {
 export declare function validateContractStructure(contractData: unknown, schema: object): ContractStructureValidation;
 export declare function evaluateSurfaceCompliance(contract: InterfaceContract, descriptor: SurfaceDescriptor): SurfaceReport;
 export declare function evaluateContractCompliance(contract: InterfaceContract, descriptors: SurfaceDescriptor[]): ValidationSummary;
-export type { InterfaceContract, ContractSurface, ContractSection, ContractConstraints, SurfaceDescriptor, SurfaceSectionDescriptor, SurfaceFontDescriptor, SurfaceColorDescriptor, SurfaceMotionDescriptor, SurfaceLayoutDescriptor, PageFrameLayoutDescriptor, SurfaceReport, DriftViolation, ValidationSummary, DriftViolationType, DiffOutput, DiffEntry, DiffChangeType, DriftRisk, Severity, SafetyLevel, EnforcementPolicy, EnforcementMode, AutofixRule, FixSummary, FixEntry, FixError, } from "./types.js";
+export type { InterfaceContract, ContractSurface, ContractSection, ContractConstraints, SurfaceDescriptor, SurfaceSectionDescriptor, SurfaceFontDescriptor, SurfaceColorDescriptor, SurfaceMotionDescriptor, SurfaceLayoutDescriptor, PageFrameLayoutDescriptor, SurfaceReport, DriftViolation, ValidationSummary, DriftViolationType, ContractRef, RuleRef, DiffOutput, DiffEntry, DiffChangeType, DriftRisk, Severity, SafetyLevel, EnforcementPolicy, EnforcementMode, AutofixRule, FixSummary, FixEntry, FixError, } from "./types.js";
 export { getBundledDiffSchema, getBundledPolicySchema, getBundledFixSummarySchema, validateDiffOutput, validatePolicy, validateFixSummary, type ValidationResult, } from "./schema-validate.js";
 //# sourceMappingURL=index.d.ts.map
\ No newline at end of file
diff --git a/packages/interfacectl-validator/dist/index.d.ts.map b/packages/interfacectl-validator/dist/index.d.ts.map
index b1790f1..660d83c 100644
--- a/packages/interfacectl-validator/dist/index.d.ts.map
+++ b/packages/interfacectl-validator/dist/index.d.ts.map
@@ -1 +1 @@
-{"version":3,"file":"index.d.ts","sourceRoot":"","sources":["../src/index.ts"],"names":[],"mappings":"AAEA,OAAO,EACL,iBAAiB,EACjB,iBAAiB,EACjB,aAAa,EACb,iBAAiB,EAKlB,MAAM,YAAY,CAAC;AAOpB,wBAAgB,wBAAwB,IAAI,MAAM,CAEjD;AAED,MAAM,WAAW,2BAA2B;IAC1C,EAAE,EAAE,OAAO,CAAC;IACZ,MAAM,EAAE,MAAM,EAAE,CAAC;IACjB,QAAQ,CAAC,EAAE,iBAAiB,CAAC;CAC9B;AAED,wBAAgB,yBAAyB,CACvC,YAAY,EAAE,OAAO,EACrB,MAAM,EAAE,MAAM,GACb,2BAA2B,CAyB7B;AA4ID,wBAAgB,yBAAyB,CACvC,QAAQ,EAAE,iBAAiB,EAC3B,UAAU,EAAE,iBAAiB,GAC5B,aAAa,CAqUf;AAED,wBAAgB,0BAA0B,CACxC,QAAQ,EAAE,iBAAiB,EAC3B,WAAW,EAAE,iBAAiB,EAAE,GAC/B,iBAAiB,CA6CnB;AAyCD,YAAY,EACV,iBAAiB,EACjB,eAAe,EACf,eAAe,EACf,mBAAmB,EACnB,iBAAiB,EACjB,wBAAwB,EACxB,qBAAqB,EACrB,sBAAsB,EACtB,uBAAuB,EACvB,uBAAuB,EACvB,yBAAyB,EACzB,aAAa,EACb,cAAc,EACd,iBAAiB,EACjB,kBAAkB,EAClB,UAAU,EACV,SAAS,EACT,cAAc,EACd,SAAS,EACT,QAAQ,EACR,WAAW,EACX,iBAAiB,EACjB,eAAe,EACf,WAAW,EACX,UAAU,EACV,QAAQ,EACR,QAAQ,GACT,MAAM,YAAY,CAAC;AAEpB,OAAO,EACL,oBAAoB,EACpB,sBAAsB,EACtB,0BAA0B,EAC1B,kBAAkB,EAClB,cAAc,EACd,kBAAkB,EAClB,KAAK,gBAAgB,GACtB,MAAM,sBAAsB,CAAC"}
\ No newline at end of file
+{"version":3,"file":"index.d.ts","sourceRoot":"","sources":["../src/index.ts"],"names":[],"mappings":"AAEA,OAAO,EACL,iBAAiB,EACjB,iBAAiB,EACjB,aAAa,EACb,iBAAiB,EAKlB,MAAM,YAAY,CAAC;AAOpB,wBAAgB,wBAAwB,IAAI,MAAM,CAEjD;AAED,MAAM,WAAW,2BAA2B;IAC1C,EAAE,EAAE,OAAO,CAAC;IACZ,MAAM,EAAE,MAAM,EAAE,CAAC;IACjB,QAAQ,CAAC,EAAE,iBAAiB,CAAC;CAC9B;AAED,wBAAgB,yBAAyB,CACvC,YAAY,EAAE,OAAO,EACrB,MAAM,EAAE,MAAM,GACb,2BAA2B,CAyB7B;AA4ID,wBAAgB,yBAAyB,CACvC,QAAQ,EAAE,iBAAiB,EAC3B,UAAU,EAAE,iBAAiB,GAC5B,aAAa,CAqUf;AAED,wBAAgB,0BAA0B,CACxC,QAAQ,EAAE,iBAAiB,EAC3B,WAAW,EAAE,iBAAiB,EAAE,GAC/B,iBAAiB,CA6CnB;AAyCD,YAAY,EACV,iBAAiB,EACjB,eAAe,EACf,eAAe,EACf,mBAAmB,EACnB,iBAAiB,EACjB,wBAAwB,EACxB,qBAAqB,EACrB,sBAAsB,EACtB,uBAAuB,EACvB,uBAAuB,EACvB,yBAAyB,EACzB,aAAa,EACb,cAAc,EACd,iBAAiB,EACjB,kBAAkB,EAClB,WAAW,EACX,OAAO,EACP,UAAU,EACV,SAAS,EACT,cAAc,EACd,SAAS,EACT,QAAQ,EACR,WAAW,EACX,iBAAiB,EACjB,eAAe,EACf,WAAW,EACX,UAAU,EACV,QAAQ,EACR,QAAQ,GACT,MAAM,YAAY,CAAC;AAEpB,OAAO,EACL,oBAAoB,EACpB,sBAAsB,EACtB,0BAA0B,EAC1B,kBAAkB,EAClB,cAAc,EACd,kBAAkB,EAClB,KAAK,gBAAgB,GACtB,MAAM,sBAAsB,CAAC"}
\ No newline at end of file
diff --git a/packages/interfacectl-validator/dist/schema/interfacectl.diff.schema.json b/packages/interfacectl-validator/dist/schema/interfacectl.diff.schema.json
index a31a2d8..5dc7259 100644
--- a/packages/interfacectl-validator/dist/schema/interfacectl.diff.schema.json
+++ b/packages/interfacectl-validator/dist/schema/interfacectl.diff.schema.json
@@ -132,6 +132,27 @@
       "type": "string",
       "enum": ["added", "removed", "modified", "renamed"]
     },
+    "ContractRef": {
+      "type": "object",
+      "description": "Reference to contract structure when deterministically derivable.",
+      "additionalProperties": false,
+      "properties": {
+        "path": { "type": "string", "description": "JSON pointer style path into the contract." },
+        "surfaceId": { "type": "string", "description": "Surface identifier when available." },
+        "sectionId": { "type": "string", "description": "Section identifier when available." },
+        "constraintId": { "type": "string", "description": "Constraint category when applicable (e.g. motion)." }
+      }
+    },
+    "RuleRef": {
+      "type": "object",
+      "description": "Reference to the rule that produced this entry.",
+      "additionalProperties": false,
+      "required": ["id"],
+      "properties": {
+        "id": { "type": "string", "minLength": 1, "description": "Stable rule identifier." },
+        "version": { "type": "string", "description": "Optional rule version when catalog exists." }
+      }
+    },
     "DiffEntry": {
       "type": "object",
       "additionalProperties": false,
@@ -170,7 +191,14 @@
             "toPath": { "type": "string", "minLength": 1 },
             "confidence": { "type": "number", "minimum": 0, "maximum": 1 }
           }
-        }
+        },
+        "stableId": {
+          "type": "string",
+          "description": "Deterministic id for correlation across runs.",
+          "minLength": 1
+        },
+        "contractRef": { "$ref": "#/$defs/ContractRef" },
+        "ruleRef": { "$ref": "#/$defs/RuleRef" }
       },
       "allOf": [
         {
diff --git a/packages/interfacectl-validator/dist/schema/interfacectl.fix-summary.schema.json b/packages/interfacectl-validator/dist/schema/interfacectl.fix-summary.schema.json
index ccb7161..5676bcd 100644
--- a/packages/interfacectl-validator/dist/schema/interfacectl.fix-summary.schema.json
+++ b/packages/interfacectl-validator/dist/schema/interfacectl.fix-summary.schema.json
@@ -34,6 +34,26 @@
     }
   },
   "$defs": {
+    "ContractRef": {
+      "type": "object",
+      "description": "Reference to contract structure when deterministically derivable.",
+      "additionalProperties": false,
+      "properties": {
+        "path": { "type": "string" },
+        "surfaceId": { "type": "string" },
+        "sectionId": { "type": "string" },
+        "constraintId": { "type": "string" }
+      }
+    },
+    "RuleRef": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["id"],
+      "properties": {
+        "id": { "type": "string", "minLength": 1 },
+        "version": { "type": "string" }
+      }
+    },
     "FixEntry": {
       "type": "object",
       "additionalProperties": false,
@@ -51,7 +71,10 @@
         "lineDelta": {
           "type": "integer",
           "description": "Optional net line change count for patch summaries."
-        }
+        },
+        "stableId": { "type": "string", "minLength": 1 },
+        "contractRef": { "$ref": "#/$defs/ContractRef" },
+        "ruleRef": { "$ref": "#/$defs/RuleRef" }
       }
     },
     "FixError": {
@@ -61,7 +84,10 @@
       "properties": {
         "ruleId": { "type": "string", "minLength": 1 },
         "path": { "type": "string", "minLength": 1 },
-        "message": { "type": "string", "minLength": 1 }
+        "message": { "type": "string", "minLength": 1 },
+        "stableId": { "type": "string", "minLength": 1 },
+        "contractRef": { "$ref": "#/$defs/ContractRef" },
+        "ruleRef": { "$ref": "#/$defs/RuleRef" }
       }
     }
   }
diff --git a/packages/interfacectl-validator/dist/types.d.ts b/packages/interfacectl-validator/dist/types.d.ts
index 07ad9ee..5ee66dc 100644
--- a/packages/interfacectl-validator/dist/types.d.ts
+++ b/packages/interfacectl-validator/dist/types.d.ts
@@ -131,6 +131,16 @@ export type DiffChangeType = "added" | "removed" | "modified" | "renamed";
 export type Severity = "error" | "warning" | "info";
 export type SafetyLevel = "safe" | "mechanical" | "semantic";
 export type EnforcementMode = "fail" | "fix" | "pr";
+export interface ContractRef {
+    path?: string;
+    surfaceId?: string;
+    sectionId?: string;
+    constraintId?: string;
+}
+export interface RuleRef {
+    id: string;
+    version?: string;
+}
 export interface DiffEntry {
     surfaceId?: string;
     type: DiffChangeType;
@@ -145,6 +155,12 @@ export interface DiffEntry {
         toPath: string;
         confidence: number;
     };
+    /** Deterministic id for correlation across runs (Phase 2 traceability) */
+    stableId?: string;
+    /** Reference to contract structure when deterministically derivable */
+    contractRef?: ContractRef;
+    /** Reference to the rule that produced this entry */
+    ruleRef?: RuleRef;
 }
 export interface DriftRisk {
     category: "diff-noise" | "semantic-ambiguity" | "enforcement-overreach" | "policy-drift" | "contract-evolution" | "observed-instability" | "rename-inflation" | "output-schema-drift" | "severity-inflation" | "local-ci-mismatch";
@@ -239,11 +255,23 @@ export interface FixEntry {
     confidence: number;
     file?: string;
     lineDelta?: number;
+    /** Deterministic id for correlation across runs (Phase 2 traceability) */
+    stableId?: string;
+    /** Reference to contract structure when deterministically derivable */
+    contractRef?: ContractRef;
+    /** Reference to the rule that produced this entry */
+    ruleRef?: RuleRef;
 }
 export interface FixError {
     ruleId: string;
     path: string;
     message: string;
+    /** Deterministic id for correlation across runs (Phase 2 traceability) */
+    stableId?: string;
+    /** Reference to contract structure when deterministically derivable */
+    contractRef?: ContractRef;
+    /** Reference to the rule that produced this entry */
+    ruleRef?: RuleRef;
 }
 export interface FixSummary {
     schemaVersion: string;
diff --git a/packages/interfacectl-validator/dist/types.d.ts.map b/packages/interfacectl-validator/dist/types.d.ts.map
index f7a0502..30e3346 100644
--- a/packages/interfacectl-validator/dist/types.d.ts.map
+++ b/packages/interfacectl-validator/dist/types.d.ts.map
@@ -1 +1 @@
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\ No newline at end of file
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\ No newline at end of file
diff --git a/packages/interfacectl-validator/src/index.ts b/packages/interfacectl-validator/src/index.ts
index 0238eee..160436c 100644
--- a/packages/interfacectl-validator/src/index.ts
+++ b/packages/interfacectl-validator/src/index.ts
@@ -629,6 +629,8 @@ export type {
   DriftViolation,
   ValidationSummary,
   DriftViolationType,
+  ContractRef,
+  RuleRef,
   DiffOutput,
   DiffEntry,
   DiffChangeType,
diff --git a/packages/interfacectl-validator/src/schema/interfacectl.diff.schema.json b/packages/interfacectl-validator/src/schema/interfacectl.diff.schema.json
index a31a2d8..5dc7259 100644
--- a/packages/interfacectl-validator/src/schema/interfacectl.diff.schema.json
+++ b/packages/interfacectl-validator/src/schema/interfacectl.diff.schema.json
@@ -132,6 +132,27 @@
       "type": "string",
       "enum": ["added", "removed", "modified", "renamed"]
     },
+    "ContractRef": {
+      "type": "object",
+      "description": "Reference to contract structure when deterministically derivable.",
+      "additionalProperties": false,
+      "properties": {
+        "path": { "type": "string", "description": "JSON pointer style path into the contract." },
+        "surfaceId": { "type": "string", "description": "Surface identifier when available." },
+        "sectionId": { "type": "string", "description": "Section identifier when available." },
+        "constraintId": { "type": "string", "description": "Constraint category when applicable (e.g. motion)." }
+      }
+    },
+    "RuleRef": {
+      "type": "object",
+      "description": "Reference to the rule that produced this entry.",
+      "additionalProperties": false,
+      "required": ["id"],
+      "properties": {
+        "id": { "type": "string", "minLength": 1, "description": "Stable rule identifier." },
+        "version": { "type": "string", "description": "Optional rule version when catalog exists." }
+      }
+    },
     "DiffEntry": {
       "type": "object",
       "additionalProperties": false,
@@ -170,7 +191,14 @@
             "toPath": { "type": "string", "minLength": 1 },
             "confidence": { "type": "number", "minimum": 0, "maximum": 1 }
           }
-        }
+        },
+        "stableId": {
+          "type": "string",
+          "description": "Deterministic id for correlation across runs.",
+          "minLength": 1
+        },
+        "contractRef": { "$ref": "#/$defs/ContractRef" },
+        "ruleRef": { "$ref": "#/$defs/RuleRef" }
       },
       "allOf": [
         {
diff --git a/packages/interfacectl-validator/src/schema/interfacectl.fix-summary.schema.json b/packages/interfacectl-validator/src/schema/interfacectl.fix-summary.schema.json
index ccb7161..5676bcd 100644
--- a/packages/interfacectl-validator/src/schema/interfacectl.fix-summary.schema.json
+++ b/packages/interfacectl-validator/src/schema/interfacectl.fix-summary.schema.json
@@ -34,6 +34,26 @@
     }
   },
   "$defs": {
+    "ContractRef": {
+      "type": "object",
+      "description": "Reference to contract structure when deterministically derivable.",
+      "additionalProperties": false,
+      "properties": {
+        "path": { "type": "string" },
+        "surfaceId": { "type": "string" },
+        "sectionId": { "type": "string" },
+        "constraintId": { "type": "string" }
+      }
+    },
+    "RuleRef": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["id"],
+      "properties": {
+        "id": { "type": "string", "minLength": 1 },
+        "version": { "type": "string" }
+      }
+    },
     "FixEntry": {
       "type": "object",
       "additionalProperties": false,
@@ -51,7 +71,10 @@
         "lineDelta": {
           "type": "integer",
           "description": "Optional net line change count for patch summaries."
-        }
+        },
+        "stableId": { "type": "string", "minLength": 1 },
+        "contractRef": { "$ref": "#/$defs/ContractRef" },
+        "ruleRef": { "$ref": "#/$defs/RuleRef" }
       }
     },
     "FixError": {
@@ -61,7 +84,10 @@
       "properties": {
         "ruleId": { "type": "string", "minLength": 1 },
         "path": { "type": "string", "minLength": 1 },
-        "message": { "type": "string", "minLength": 1 }
+        "message": { "type": "string", "minLength": 1 },
+        "stableId": { "type": "string", "minLength": 1 },
+        "contractRef": { "$ref": "#/$defs/ContractRef" },
+        "ruleRef": { "$ref": "#/$defs/RuleRef" }
       }
     }
   }
diff --git a/packages/interfacectl-validator/src/types.ts b/packages/interfacectl-validator/src/types.ts
index 339e7f3..8379dc6 100644
--- a/packages/interfacectl-validator/src/types.ts
+++ b/packages/interfacectl-validator/src/types.ts
@@ -177,6 +177,18 @@ export type Severity = "error" | "warning" | "info";
 export type SafetyLevel = "safe" | "mechanical" | "semantic";
 export type EnforcementMode = "fail" | "fix" | "pr";
 
+export interface ContractRef {
+  path?: string;
+  surfaceId?: string;
+  sectionId?: string;
+  constraintId?: string;
+}
+
+export interface RuleRef {
+  id: string;
+  version?: string;
+}
+
 export interface DiffEntry {
   surfaceId?: string;
   type: DiffChangeType;
@@ -191,6 +203,12 @@ export interface DiffEntry {
     toPath: string;
     confidence: number; // 0-1
   }; // Only present when type=renamed
+  /** Deterministic id for correlation across runs (Phase 2 traceability) */
+  stableId?: string;
+  /** Reference to contract structure when deterministically derivable */
+  contractRef?: ContractRef;
+  /** Reference to the rule that produced this entry */
+  ruleRef?: RuleRef;
 }
 
 export interface DriftRisk {
@@ -264,12 +282,24 @@ export interface FixEntry {
   confidence: number; // 0-1
   file?: string; // Relative path only
   lineDelta?: number;
+  /** Deterministic id for correlation across runs (Phase 2 traceability) */
+  stableId?: string;
+  /** Reference to contract structure when deterministically derivable */
+  contractRef?: ContractRef;
+  /** Reference to the rule that produced this entry */
+  ruleRef?: RuleRef;
 }
 
 export interface FixError {
   ruleId: string;
   path: string;
   message: string;
+  /** Deterministic id for correlation across runs (Phase 2 traceability) */
+  stableId?: string;
+  /** Reference to contract structure when deterministically derivable */
+  contractRef?: ContractRef;
+  /** Reference to the rule that produced this entry */
+  ruleRef?: RuleRef;
 }
 
 export interface FixSummary {