diff --git a/.ci/argo-workflows/pdftract-ci.yaml b/.ci/argo-workflows/pdftract-ci.yaml
index 87d3c56..1f25f9d 100644
--- a/.ci/argo-workflows/pdftract-ci.yaml
+++ b/.ci/argo-workflows/pdftract-ci.yaml
@@ -35,7 +35,7 @@
 # - setup: Clone repo, fetch dependencies, warm cargo cache
 # - build-matrix: Cross-compile for 5 targets (x86_64/aarch64 Linux musl, macOS x64/ARM64, Windows x64)
 # - test-matrix: Run unit tests across feature combinations (default, full, with OCR)
-# - quality-matrix: Five Tier 1 quality gates (clippy-fmt, msrv-check, cargo-audit, cargo-deny, cargo-bloat)
+# - quality-matrix: Seven Tier 1 quality gates (clippy-fmt, msrv-check, cargo-audit, cargo-deny, cargo-bloat, memory-ceiling, schema-gen)
 # - bench-matrix: Performance benchmarks (cargo bench) against fixture corpus
 # - publish-if-tag: On tags only, upload binaries to GitHub Releases
 #
@@ -269,6 +269,7 @@ spec:
           add_step "cargo-deny" "$WORKFLOW_PHASE"
           add_step "cargo-bloat" "$WORKFLOW_PHASE"
           add_step "memory-ceiling" "$WORKFLOW_PHASE"
+          add_step "schema-gen" "$WORKFLOW_PHASE"
           add_step "wer-gate" "$WORKFLOW_PHASE"
           add_step "bench-matrix" "$WORKFLOW_PHASE"
           add_step "regression-corpus" "$WORKFLOW_PHASE"
@@ -1135,9 +1136,9 @@ spec:
     # === Quality Matrix ===
     # Run linting (clippy, fmt), security audit (cargo-audit), dependency review,
     # license/ban/advisory checks (cargo-deny), MSRV check, binary size budget,
-    # and memory ceiling enforcement.
+    # memory ceiling enforcement, and schema generation consistency.
     #
-    # Six parallel Tier 1 quality gates — any failure blocks PR merge:
+    # Seven parallel Tier 1 quality gates — any failure blocks PR merge:
     # 1. clippy-fmt: General linting and formatting check with INV-8 unwrap/expect ban
     # 2. msrv-check: Verify no newer Rust features are used (MSRV 1.78)
     # 3. cargo-audit: Security advisory check on dependencies
@@ -1162,6 +1163,8 @@ spec:
             template: cargo-bloat
           - name: memory-ceiling
             template: memory-ceiling
+          - name: schema-gen
+            template: schema-gen
 
     # === Clippy and Fmt Check ===
     # Runs clippy with warnings denied and INV-8 unwrap/expect enforcement.
@@ -1845,6 +1848,96 @@ spec:
           - name: memory-report
             path: /workspace/memory-report.json
 
+    # === Schema Generation Check ===
+    # Regenerates JSON schema from Rust types and verifies it matches the committed file.
+    #
+    # This is a Tier 1 hard gate from Phase 6.1.3. It ensures the auto-generated schema
+    # stays in sync with the Rust type definitions. Without this gate, schema drift
+    # silently slips past code review and the published schema becomes incorrect.
+    #
+    # Bead: pdftract-16h0a
+    # Plan section: Phase 6.1.3
+    #
+    # Enforcement policy:
+    # - Schema is regenerated via cargo xtask gen-schema
+    # - Regenerated output is compared to committed docs/schema/v1.0/pdftract.schema.json
+    # - Any diff (including whitespace, key order) fails the build
+    # - Error message includes exact reproduction command
+    # - Schema changes involving Phase 7 placeholders are backward-compatible additions
+    # - Breaking changes require explicit schema_version bump (separate bead)
+    - name: schema-gen
+      activeDeadlineSeconds: 300
+      container:
+        image: pdftract-test-glibc:1.78
+        command: [bash, -c]
+        args:
+          - |
+            set -eo pipefail
+
+            echo "=========================================="
+            echo "Schema Generation Check"
+            echo "=========================================="
+
+            cd /workspace
+            export CARGO_HOME="/cache/cargo/registry"
+            export CARGO_TARGET_DIR="/cache/cargo/target-schema-gen"
+
+            echo "=== Regenerating JSON schema ==="
+            echo "Command: cargo xtask gen-schema"
+            cd /workspace/xtask && cargo run --release -- gen-schema || {
+              EXIT_CODE=$?
+
+              echo "=========================================="
+              echo "SCHEMA GENERATION FAILED"
+              echo "=========================================="
+              echo ""
+              echo "The schema generation command crashed with exit code $EXIT_CODE."
+              echo "This is likely a bug in the generator, not a schema mismatch."
+              echo ""
+              echo "Check the output above for specific errors."
+
+              exit $EXIT_CODE
+            }
+
+            echo ""
+            echo "=== Comparing to committed schema ==="
+            SCHEMA_FILE="docs/schema/v1.0/pdftract.schema.json"
+
+            if ! git diff --exit-code "$SCHEMA_FILE"; then
+              echo "=========================================="
+              echo "SCHEMA MISMATCH DETECTED"
+              echo "=========================================="
+              echo ""
+              echo "The regenerated schema differs from the committed file:"
+              echo "  File: $SCHEMA_FILE"
+              echo ""
+              echo "To fix this issue:"
+              echo "  1. Run locally: cargo xtask gen-schema"
+              echo "  2. Commit the regenerated schema file"
+              echo "  3. Push the commit"
+              echo ""
+              echo "Diff:"
+              git diff "$SCHEMA_FILE"
+
+              exit 1
+            fi
+
+            echo ""
+            echo "=== Schema generation check passed ==="
+            echo "Schema is up to date: $SCHEMA_FILE"
+        volumeMounts:
+          - name: workspace
+            mountPath: /workspace
+          - name: cargo-cache
+            mountPath: /cache/cargo
+        resources:
+          requests:
+            cpu: 1000m
+            memory: 2Gi
+          limits:
+            cpu: 2000m
+            memory: 4Gi
+
     # === WER Gate ===
     # Word Error Rate CI gate for OCR accuracy validation
     #