feat: release-to-release delta in export + CI snapshot workflow

.github/workflows/release.yml

@@ -92,7 +92,42 @@ jobs:
           name: binary-${{ matrix.target }}
           path: ${{ env.ARCHIVE }}
 
+  # ── Baseline snapshot ─────────────────────────────────────────────────
+  capture-snapshot:
+    name: Capture baseline snapshot
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Capture snapshot
+        env:
+          TAG: ${{ github.ref_name }}
+        run: cargo run --release -- snapshot capture --name "$TAG"
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: snapshot
+          path: snapshots/
+
+      - name: Commit snapshot to main
+        env:
+          TAG: ${{ github.ref_name }}
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add snapshots/
+          git diff --cached --quiet && exit 0
+          git commit -m "chore: capture baseline snapshot for $TAG"
+          git push origin HEAD:main || true
+
   # ── Compliance report (HTML export) ───────────────────────────────────
+  # Uses snapshots already committed from PREVIOUS releases (not the one
+  # just captured). The new snapshot is for future release comparisons.
   build-compliance:
     name: Build compliance report
     runs-on: ubuntu-latest

rivet-cli/src/main.rs

@@ -2721,7 +2721,21 @@ fn cmd_export_html(
     // Load project state using the same pipeline as `rivet serve`.
     let state = serve::reload_state(&project_path, &schemas_dir, 0)
         .context("loading project for export")?;
-    let ctx = state.as_render_context();
+
+    // Auto-detect baseline snapshot for delta rendering.
+    let snap_dir = project_path.join("snapshots");
+    let baseline_snapshot = find_latest_snapshot(&snap_dir)
+        .ok()
+        .and_then(|path| rivet_core::snapshot::read_from_file(&path).ok());
+    if let Some(ref snap) = baseline_snapshot {
+        eprintln!(
+            "delta: comparing against baseline {} ({})",
+            snap.git_commit_short, snap.created_at,
+        );
+    }
+
+    let mut ctx = state.as_render_context();
+    ctx.baseline = baseline_snapshot.as_ref();
     let params = ViewParams::default();
 
     // SC-EMBED-1: warn when working tree is dirty.
@@ -5667,6 +5681,7 @@ fn cmd_lsp(cli: &Cli) -> Result<bool> {
                             externals: &externals,
                             project_path: &project_dir,
                             schemas_dir: &schemas_dir,
+                            baseline: None,
                         };
 
                         let result = crate::render::render_page(&ctx, page, &view_params);

rivet-cli/src/render/coverage.rs

@@ -1,3 +1,5 @@
+use std::fmt::Write as _;
+
 use rivet_core::coverage;
 use rivet_core::document::html_escape;
 
@@ -44,8 +46,15 @@ pub(crate) fn render_coverage_view(ctx: &RenderContext) -> String {
         return html;
     }
 
+    let bl = ctx.baseline;
+    let has_delta = bl.is_some();
+
     html.push_str("<div class=\"card\"><h3>Coverage by Rule</h3>");
-    html.push_str("<table><thead><tr><th>Rule</th><th>Source Type</th><th>Link</th><th>Direction</th><th>Coverage</th><th style=\"width:30%\">Progress</th></tr></thead><tbody>");
+    if has_delta {
+        html.push_str("<table><thead><tr><th>Rule</th><th>Source Type</th><th>Link</th><th>Direction</th><th>Coverage</th><th>Δ</th><th style=\"width:25%\">Progress</th></tr></thead><tbody>");
+    } else {
+        html.push_str("<table><thead><tr><th>Rule</th><th>Source Type</th><th>Link</th><th>Direction</th><th>Coverage</th><th style=\"width:30%\">Progress</th></tr></thead><tbody>");
+    }
 
     for entry in &report.entries {
         let pct = entry.percentage();
@@ -62,28 +71,48 @@ pub(crate) fn render_coverage_view(ctx: &RenderContext) -> String {
             coverage::CoverageDirection::Backward => "backward",
         };
 
-        html.push_str(&format!(
+        let delta_cell = if has_delta {
+            let base_pct = bl
+                .and_then(|s| s.coverage.rules.iter().find(|r| r.rule == entry.rule_name))
+                .map_or(0.0, |r| r.percentage);
+            let diff = pct - base_pct;
+            if diff.abs() < 0.05 {
+                "<td>—</td>".to_string()
+            } else {
+                let (sign, color) = if diff > 0.0 {
+                    ("+", "#15713a")
+                } else {
+                    ("", "#c62828")
+                };
+                format!("<td style=\"color:{color};font-weight:600\">{sign}{diff:.1}%</td>")
+            }
+        } else {
+            String::new()
+        };
+
+        let _ = write!(
+            html,
             "<tr>\
-             <td title=\"{}\">{}</td>\
-             <td>{}</td>\
-             <td><span class=\"link-pill\">{}</span></td>\
-             <td>{}</td>\
-             <td><span class=\"badge {badge_class}\">{}/{} ({:.1}%)</span></td>\
+             <td title=\"{desc}\">{name}</td>\
+             <td>{source}</td>\
+             <td><span class=\"link-pill\">{link}</span></td>\
+             <td>{dir}</td>\
+             <td><span class=\"badge {badge_class}\">{covered}/{total} ({pct:.1}%)</span></td>\
+             {delta_cell}\
              <td>\
                <div style=\"background:#e5e5ea;border-radius:4px;height:18px;position:relative;overflow:hidden\">\
                  <div style=\"background:{bar_color};height:100%;width:{pct:.1}%;border-radius:4px;transition:width .3s ease\"></div>\
                </div>\
              </td>\
              </tr>",
-            html_escape(&entry.description),
-            html_escape(&entry.rule_name),
-            badge_for_type(&entry.source_type),
-            html_escape(&entry.link_type),
-            dir_label,
-            entry.covered,
-            entry.total,
-            pct,
-        ));
+            desc = html_escape(&entry.description),
+            name = html_escape(&entry.rule_name),
+            source = badge_for_type(&entry.source_type),
+            link = html_escape(&entry.link_type),
+            dir = dir_label,
+            covered = entry.covered,
+            total = entry.total,
+        );
     }
 
     html.push_str("</tbody></table></div>");

rivet-cli/src/render/mod.rs

@@ -42,6 +42,8 @@ pub(crate) struct RenderContext<'a> {
     pub(crate) externals: &'a [ExternalInfo],
     pub(crate) project_path: &'a Path,
     pub(crate) schemas_dir: &'a Path,
+    /// Optional baseline snapshot for delta rendering in export.
+    pub(crate) baseline: Option<&'a rivet_core::snapshot::Snapshot>,
 }
 
 #[allow(dead_code)]

rivet-cli/src/render/stats.rs

@@ -1,4 +1,5 @@
 use std::collections::BTreeMap;
+use std::fmt::Write as _;
 
 use rivet_core::coverage;
 use rivet_core::document::html_escape;
@@ -7,6 +8,36 @@ use rivet_core::schema::Severity;
 use crate::render::RenderContext;
 use crate::render::helpers::badge_for_type;
 
+/// Render a delta badge like `+3` or `-2` with green/red styling.
+fn delta_badge(current: usize, baseline: usize) -> String {
+    let diff = current as isize - baseline as isize;
+    if diff == 0 {
+        return String::new();
+    }
+    let (sign, color) = if diff > 0 {
+        ("+", "#15713a")
+    } else {
+        ("", "#c62828")
+    };
+    format!(" <span style=\"font-size:.75em;color:{color};font-weight:600\">{sign}{diff}</span>")
+}
+
+/// Render a delta badge for percentages.
+fn delta_pct_badge(current: f64, baseline: f64) -> String {
+    let diff = current - baseline;
+    if diff.abs() < 0.05 {
+        return String::new();
+    }
+    let (sign, color) = if diff > 0.0 {
+        ("+", "#15713a")
+    } else {
+        ("", "#c62828")
+    };
+    format!(
+        " <span style=\"font-size:.75em;color:{color};font-weight:600\">{sign}{diff:.1}%</span>"
+    )
+}
+
 pub(crate) fn render_stats(ctx: &RenderContext) -> String {
     let store = ctx.store;
     let graph = ctx.graph;
@@ -37,46 +68,79 @@ pub(crate) fn render_stats(ctx: &RenderContext) -> String {
         ctx.schema.traceability_rules.len(),
     );
 
-    // Summary cards with colored accents
+    // Summary cards with colored accents + delta badges
+    let bl = ctx.baseline;
     html.push_str("<div class=\"stat-grid\">");
-    html.push_str(&format!(
-        "<div class=\"stat-box stat-blue\"><div class=\"number\">{}</div><div class=\"label\">Artifacts</div></div>",
-        store.len()
-    ));
-    html.push_str(&format!(
+    let _ = write!(
+        html,
+        "<div class=\"stat-box stat-blue\"><div class=\"number\">{}{}</div><div class=\"label\">Artifacts</div></div>",
+        store.len(),
+        bl.map_or(String::new(), |s| delta_badge(store.len(), s.stats.total)),
+    );
+    let _ = write!(
+        html,
         "<div class=\"stat-box stat-green\"><div class=\"number\">{}</div><div class=\"label\">Types</div></div>",
-        types.len()
-    ));
-    html.push_str(&format!(
+        types.len(),
+    );
+    let _ = write!(
+        html,
         "<div class=\"stat-box stat-orange\"><div class=\"number\">{}</div><div class=\"label\">Orphans</div></div>",
-        orphans.len()
-    ));
-    html.push_str(&format!(
-        "<div class=\"stat-box stat-red\"><div class=\"number\">{}</div><div class=\"label\">Errors</div></div>",
-        errors
-    ));
-    html.push_str(&format!(
-        "<div class=\"stat-box stat-amber\"><div class=\"number\">{}</div><div class=\"label\">Warnings</div></div>",
-        warnings
-    ));
-    html.push_str(&format!(
+        orphans.len(),
+    );
+    let _ = write!(
+        html,
+        "<div class=\"stat-box stat-red\"><div class=\"number\">{}{}</div><div class=\"label\">Errors</div></div>",
+        errors,
+        bl.map_or(String::new(), |s| delta_badge(errors, s.diagnostics.errors)),
+    );
+    let _ = write!(
+        html,
+        "<div class=\"stat-box stat-amber\"><div class=\"number\">{}{}</div><div class=\"label\">Warnings</div></div>",
+        warnings,
+        bl.map_or(String::new(), |s| delta_badge(
+            warnings,
+            s.diagnostics.warnings
+        )),
+    );
+    let _ = write!(
+        html,
         "<div class=\"stat-box stat-purple\"><div class=\"number\">{}</div><div class=\"label\">Broken Links</div></div>",
-        graph.broken.len()
-    ));
-    html.push_str(&format!(
+        graph.broken.len(),
+    );
+    let _ = write!(
+        html,
         "<div class=\"stat-box stat-blue\"><div class=\"number\">{}</div><div class=\"label\">Documents</div></div>",
-        doc_store.len()
-    ));
+        doc_store.len(),
+    );
     html.push_str("</div>");
 
     // By-type table
-    html.push_str("<div class=\"card\"><h3>Artifacts by Type</h3><table><thead><tr><th>Type</th><th>Count</th></tr></thead><tbody>");
+    let has_delta = bl.is_some();
+    if has_delta {
+        html.push_str("<div class=\"card\"><h3>Artifacts by Type</h3><table><thead><tr><th>Type</th><th>Count</th><th>Δ</th></tr></thead><tbody>");
+    } else {
+        html.push_str("<div class=\"card\"><h3>Artifacts by Type</h3><table><thead><tr><th>Type</th><th>Count</th></tr></thead><tbody>");
+    }
     for t in &types {
-        html.push_str(&format!(
-            "<tr><td>{}</td><td>{}</td></tr>",
-            badge_for_type(t),
-            store.count_by_type(t)
-        ));
+        let count = store.count_by_type(t);
+        if has_delta {
+            let base_count = bl
+                .and_then(|s| s.stats.by_type.get(*t))
+                .copied()
+                .unwrap_or(0);
+            let _ = write!(
+                html,
+                "<tr><td>{}</td><td>{count}</td><td>{}</td></tr>",
+                badge_for_type(t),
+                delta_badge(count, base_count),
+            );
+        } else {
+            let _ = write!(
+                html,
+                "<tr><td>{}</td><td>{count}</td></tr>",
+                badge_for_type(t),
+            );
+        }
     }
     html.push_str("</tbody></table></div>");
 
@@ -134,11 +198,14 @@ pub(crate) fn render_stats(ctx: &RenderContext) -> String {
         };
         let total_covered: usize = cov_report.entries.iter().map(|e| e.covered).sum();
         let total_items: usize = cov_report.entries.iter().map(|e| e.total).sum();
+        let cov_delta = bl.map_or(String::new(), |s| {
+            delta_pct_badge(overall, s.coverage.overall)
+        });
         html.push_str(&format!(
             "<div class=\"card\">\
              <h3>Traceability Coverage</h3>\
              <div style=\"display:flex;align-items:center;gap:1.5rem;margin-bottom:0.75rem\">\
-               <div style=\"font-size:2rem;font-weight:700;color:{cov_color}\">{overall:.0}%</div>\
+               <div style=\"font-size:2rem;font-weight:700;color:{cov_color}\">{overall:.0}%{cov_delta}</div>\
                <div style=\"flex:1\">\
                  <div class=\"status-bar-track\" style=\"height:0.6rem\">\
                    <div class=\"status-bar-fill\" style=\"background:{cov_color};width:{overall:.1}%\"></div>\

rivet-cli/src/serve/mod.rs

@@ -208,6 +208,7 @@ impl AppState {
             externals: &self.externals,
             project_path: &self.project_path_buf,
             schemas_dir: &self.schemas_dir,
+            baseline: None,
         }
     }
 }