diff --git a/rivet-cli/src/main.rs b/rivet-cli/src/main.rs
index 9b0a8331..33cc5951 100644
--- a/rivet-cli/src/main.rs
+++ b/rivet-cli/src/main.rs
@@ -7352,6 +7352,7 @@ fn cmd_export(
             homepage,
             version_label,
             versions_json,
+            sexpr_filter,
         );
     }
 
@@ -7979,6 +7980,7 @@ fn cmd_export_html(
     _homepage: Option<&str>,
     _version_label: Option<&str>,
     _versions_json: Option<&str>,
+    sexpr_filter: Option<&str>,
 ) -> Result<bool> {
     use crate::render::styles;
     use crate::serve::components::ViewParams;
@@ -8079,7 +8081,14 @@ fn cmd_export_html(
         .filter(|d| d.severity == rivet_core::schema::Severity::Error)
         .count();
 
-    let wrap_page = |title: &str, content: &str| -> String {
+    let wrap_page = |title: &str, content: &str, rel_path: &str| -> String {
+        // REQ-088: depth-adjusted prefix so per-page asset and nav hrefs
+        // work for pages at any nesting (root, depth-1, depth-2, …).
+        // `rel_path` is the page's path relative to `out_dir`, e.g.
+        // "index.html" (depth 0) or "artifacts/foo.html" (depth 1) or
+        // "help/schema/foo.html" (depth 2).
+        let depth = rel_path.matches('/').count();
+        let prefix: String = "../".repeat(depth);
         let version = env!("CARGO_PKG_VERSION");
         let project_name = &state.context.project_name;
         let error_badge = if error_count > 0 {
@@ -8111,7 +8120,7 @@ fn cmd_export_html(
             .sum();
         let stpa_nav = if stpa_count > 0 {
             format!(
-                "<li><a href=\"stpa/index.html\">STPA \
+                "<li><a href=\"{prefix}stpa/index.html\">STPA \
                  <span class=\"nav-badge\">{stpa_count}</span></a></li>"
             )
         } else {
@@ -8128,7 +8137,7 @@ fn cmd_export_html(
             } else {
                 String::new()
             };
-            format!("<li><a href=\"../eu-ai-act/index.html\">EU AI Act{badge}</a></li>")
+            format!("<li><a href=\"{prefix}eu-ai-act/index.html\">EU AI Act{badge}</a></li>")
         } else {
             String::new()
         };
@@ -8139,8 +8148,8 @@ fn cmd_export_html(
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width,initial-scale=1">
 <title>{title} — {project_name} — Rivet</title>
-<style>{fonts_css}{css}</style>
-<script>{mermaid_js}</script>
+<link rel="stylesheet" href="{prefix}_assets/styles.css">
+<script src="{prefix}_assets/mermaid.min.js"></script>
 <script>
 mermaid.initialize({{startOnLoad:false,theme:'neutral',securityLevel:'strict'}});
 document.addEventListener('DOMContentLoaded',function(){{
@@ -8153,21 +8162,21 @@ document.addEventListener('DOMContentLoaded',function(){{
 <nav role="navigation" aria-label="Main navigation">
   <h1>Rivet</h1>
   <ul>
-    <li><a href="../index.html">Overview
+    <li><a href="{prefix}index.html">Overview
       <span class="nav-badge">{artifact_count}</span></a></li>
-    <li><a href="../artifacts/index.html">Artifacts
+    <li><a href="{prefix}artifacts/index.html">Artifacts
       <span class="nav-badge">{artifact_count}</span></a></li>
-    <li><a href="../validate/index.html">Validation
+    <li><a href="{prefix}validate/index.html">Validation
       {error_badge}</a></li>
     <li class="nav-divider"></li>
-    <li><a href="../matrix/index.html">Matrix</a></li>
-    <li><a href="../coverage/index.html">Coverage</a></li>
-    <li><a href="../graph/index.html">Graph</a></li>
-    <li><a href="../documents/index.html">Documents{doc_badge}</a></li>
+    <li><a href="{prefix}matrix/index.html">Matrix</a></li>
+    <li><a href="{prefix}coverage/index.html">Coverage</a></li>
+    <li><a href="{prefix}graph/index.html">Graph</a></li>
+    <li><a href="{prefix}documents/index.html">Documents{doc_badge}</a></li>
     <li class="nav-divider"></li>
     {stpa_nav}
     {eu_ai_act_nav}
-    <li><a href="../help/index.html">Help &amp; Docs</a></li>
+    <li><a href="{prefix}help/index.html">Help &amp; Docs</a></li>
   </ul>
   <div style="padding:.75rem 1rem;font-size:.7rem;color:var(--sidebar-text)">
     v{version}
@@ -8176,21 +8185,35 @@ document.addEventListener('DOMContentLoaded',function(){{
 <div class="content-area">
 <main id="content" role="main">
 {content}
-<div class="footer">Generated by Rivet v{version} &mdash; <a href="index.html">Back to top</a></div>
+<div class="footer">Generated by Rivet v{version} &mdash; <a href="{prefix}index.html">Back to top</a></div>
 </main>
 </div>
 </div>
 </body>
 </html>"#,
-            fonts_css = styles::FONTS_CSS,
-            css = styles::CSS,
-            mermaid_js = MERMAID_JS,
         )
     };
 
     let out_dir = output.unwrap_or(std::path::Path::new("dist"));
     std::fs::create_dir_all(out_dir).with_context(|| format!("creating {}", out_dir.display()))?;
 
+    // REQ-088: write CSS + JS to a shared `_assets/` directory once,
+    // instead of inlining ~3MB of mermaid.min.js into every page. With
+    // 5000+ artifacts the previous per-page embed produced ~13 GB of
+    // mostly-identical bytes; this drops total export size by ~99%
+    // (4000 pages * 3MB inline -> 4000 pages of ~50KB markup + one
+    // 3MB shared asset).
+    let assets_dir = out_dir.join("_assets");
+    std::fs::create_dir_all(&assets_dir)
+        .with_context(|| format!("creating {}", assets_dir.display()))?;
+    std::fs::write(
+        assets_dir.join("styles.css"),
+        format!("{}{}", styles::FONTS_CSS, styles::CSS),
+    )
+    .with_context(|| format!("writing {}", assets_dir.join("styles.css").display()))?;
+    std::fs::write(assets_dir.join("mermaid.min.js"), MERMAID_JS)
+        .with_context(|| format!("writing {}", assets_dir.join("mermaid.min.js").display()))?;
+
     let mut page_count = 0usize;
 
     // Helper: render a page, wrap it, and write it to a relative path within out_dir.
@@ -8199,7 +8222,7 @@ document.addEventListener('DOMContentLoaded',function(){{
     let write_page =
         |rel_path: &str, page: &str, title: &str, out_dir: &std::path::Path| -> Result<()> {
             let result = render::render_page(&ctx, page, &params);
-            let html = wrap_page(title, &result.html);
+            let html = wrap_page(title, &result.html, rel_path);
             let dest = out_dir.join(rel_path);
             if let Some(parent) = dest.parent() {
                 std::fs::create_dir_all(parent)
@@ -8248,7 +8271,34 @@ document.addEventListener('DOMContentLoaded',function(){{
     page_count += 1;
 
     // ── Per-artifact detail pages ────────────────────────────────────
-    let artifact_ids: Vec<String> = state.store.iter().map(|a| a.id.clone()).collect();
+    //
+    // REQ-087: apply the s-expression `--filter` if provided so the
+    // per-artifact page set narrows to the requested subset. Previously
+    // `cmd_export` accepted `--filter` but never threaded it into
+    // `cmd_export_html`, so a filtered HTML export silently emitted
+    // every artifact — the F2 silent-failure class (flag claims a
+    // semantic the implementation does not deliver).
+    let artifact_ids: Vec<String> = if let Some(filter_src) = sexpr_filter {
+        let expr = rivet_core::sexpr_eval::parse_filter(filter_src).map_err(|errs| {
+            let msgs: Vec<String> = errs.iter().map(|e| e.to_string()).collect();
+            anyhow::anyhow!("invalid --filter expression: {}", msgs.join("; "))
+        })?;
+        state
+            .store
+            .iter()
+            .filter(|a| {
+                rivet_core::sexpr_eval::matches_filter_with_store(
+                    &expr,
+                    a,
+                    &state.graph,
+                    &state.store,
+                )
+            })
+            .map(|a| a.id.clone())
+            .collect()
+    } else {
+        state.store.iter().map(|a| a.id.clone()).collect()
+    };
     for id in &artifact_ids {
         let rel = format!("artifacts/{id}.html");
         let page = format!("/artifacts/{id}");
diff --git a/rivet-cli/tests/export_html.rs b/rivet-cli/tests/export_html.rs
new file mode 100644
index 00000000..f16a49f2
--- /dev/null
+++ b/rivet-cli/tests/export_html.rs
@@ -0,0 +1,162 @@
+// SAFETY-REVIEW (SCRC Phase 1, DD-058): Integration test code. Tests
+// legitimately use unwrap/expect/panic/assert-indexing patterns because a
+// test failure should panic with a clear stack. Same blanket allow as the
+// other integration tests in this directory.
+#![allow(
+    clippy::unwrap_used,
+    clippy::expect_used,
+    clippy::indexing_slicing,
+    clippy::arithmetic_side_effects,
+    clippy::as_conversions,
+    clippy::cast_possible_truncation,
+    clippy::cast_sign_loss,
+    clippy::wildcard_enum_match_arm,
+    clippy::match_wildcard_for_single_variants,
+    clippy::panic,
+    clippy::todo,
+    clippy::unimplemented,
+    clippy::dbg_macro,
+    clippy::print_stdout,
+    clippy::print_stderr
+)]
+
+//! Integration tests for `rivet export --html`.
+//!
+//! These run the real binary against the rivet project itself (the dogfood
+//! corpus) and assert on the structure / size of the output. The
+//! assertions verify REQ-087 (`--filter` actually narrows the per-artifact
+//! page set) and REQ-088 (CSS/JS extracted to shared `_assets/` rather
+//! than embedded per-page; per-page payload stays small).
+//!
+//! rivet: verifies REQ-087
+//! rivet: verifies REQ-088
+
+use std::process::Command;
+
+fn rivet_bin() -> std::path::PathBuf {
+    if let Ok(bin) = std::env::var("CARGO_BIN_EXE_rivet") {
+        return std::path::PathBuf::from(bin);
+    }
+    let manifest = std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"));
+    let workspace_root = manifest.parent().expect("workspace root");
+    workspace_root.join("target").join("debug").join("rivet")
+}
+
+fn project_root() -> std::path::PathBuf {
+    std::path::PathBuf::from(env!("CARGO_MANIFEST_DIR"))
+        .parent()
+        .expect("workspace root")
+        .to_path_buf()
+}
+
+fn run_export(out: &std::path::Path, filter: Option<&str>) {
+    let mut cmd = Command::new(rivet_bin());
+    cmd.args([
+        "export",
+        "--format",
+        "html",
+        "--output",
+        out.to_str().unwrap(),
+    ])
+    .current_dir(project_root());
+    if let Some(f) = filter {
+        cmd.arg("--filter").arg(f);
+    }
+    let status = cmd.status().expect("run rivet export");
+    assert!(status.success(), "rivet export exited non-zero: {status:?}");
+}
+
+fn count_html(dir: &std::path::Path) -> usize {
+    std::fs::read_dir(dir)
+        .map(|rd| {
+            rd.filter_map(Result::ok)
+                .filter(|e| e.path().extension().and_then(|s| s.to_str()) == Some("html"))
+                .count()
+        })
+        .unwrap_or(0)
+}
+
+/// REQ-088: CSS + JS are extracted to a single `_assets/` directory and
+/// referenced by relative URL; per-page HTML stays small.
+#[test]
+fn export_html_extracts_shared_assets() {
+    let tmp = tempfile::tempdir().unwrap();
+    let out = tmp.path().join("dist");
+    run_export(&out, None);
+
+    let assets = out.join("_assets");
+    assert!(
+        assets.join("styles.css").is_file(),
+        "_assets/styles.css must exist"
+    );
+    assert!(
+        assets.join("mermaid.min.js").is_file(),
+        "_assets/mermaid.min.js must exist"
+    );
+
+    // Per-artifact pages must reference assets, not embed them.
+    let artifacts = out.join("artifacts");
+    let mut sample_pages = std::fs::read_dir(&artifacts)
+        .unwrap()
+        .filter_map(Result::ok)
+        .filter(|e| e.path().extension().and_then(|s| s.to_str()) == Some("html"))
+        .filter(|e| e.file_name() != *"index.html")
+        .take(5);
+    let first = sample_pages.next().expect("at least one artifact page");
+    let body = std::fs::read_to_string(first.path()).unwrap();
+    assert!(
+        body.contains("_assets/mermaid.min.js"),
+        "per-artifact page must reference shared mermaid.min.js, got:\n{}",
+        &body[..body.len().min(2000)]
+    );
+    // The page must not contain the verbatim mermaid library source (that
+    // signature only appears when the framework is inlined).
+    assert!(
+        !body.contains("function mermaid"),
+        "per-artifact page must not embed mermaid library source"
+    );
+    let len = body.len();
+    assert!(
+        len < 100_000,
+        "per-artifact page should be <100KB (was {len} bytes); REQ-088 budget"
+    );
+}
+
+/// REQ-087: `--filter` actually narrows the per-artifact page set.
+///
+/// Uses a deliberately unmatching filter so the assertion is independent
+/// of the rivet corpus's current contents — what matters is that
+/// "filter set" -> "fewer per-artifact pages than the unfiltered baseline."
+#[test]
+fn export_html_filter_narrows_per_artifact_pages() {
+    let tmp = tempfile::tempdir().unwrap();
+
+    // Baseline: no filter, full per-artifact set.
+    let full = tmp.path().join("full");
+    run_export(&full, None);
+    let full_count = count_html(&full.join("artifacts"));
+    assert!(
+        full_count > 10,
+        "baseline should emit many per-artifact pages, got {full_count}"
+    );
+
+    // Filtered: a clause that no artifact satisfies. The per-artifact
+    // page set should drop to (effectively) just artifacts/index.html.
+    let filtered = tmp.path().join("filtered");
+    run_export(
+        &filtered,
+        Some(r#"(has-tag "this-tag-definitely-does-not-exist-anywhere")"#),
+    );
+    let filtered_count = count_html(&filtered.join("artifacts"));
+    assert!(
+        filtered_count < full_count,
+        "filter must narrow: full={full_count}, filtered={filtered_count}"
+    );
+    // Allow the artifacts/index.html shell to remain — what we're
+    // proving is the per-artifact emission honoured the filter.
+    assert!(
+        filtered_count <= 2,
+        "an unmatching filter should leave at most the index shell; \
+         got {filtered_count} pages"
+    );
+}