Create-PDF engine: render from a structured document (#7018)

app/allowed-licenses.json

@@ -208,6 +208,18 @@
       "moduleName": ".*",
       "moduleLicense": "The W3C License"
     },
+    {
+      "moduleName": "com.google.re2j:re2j",
+      "moduleLicense": "Go License"
+    },
+    {
+      "moduleName": "com.hubspot:algebra",
+      "moduleLicense": null
+    },
+    {
+      "moduleName": "com.hubspot.immutables:immutables-exceptions",
+      "moduleLicense": null
+    },
     {
       "moduleName": ".*",
       "moduleLicense": "UnRar License"

app/proprietary/build.gradle

@@ -66,6 +66,20 @@ dependencies {
 
     implementation "com.google.code.gson:gson:${gsonVersion}"
 
+    // jinjava/jjwt transitively request older Jackson 2 versions; declare the current
+    // version directly so it is selected consistently (root build.gradle pins are the fallback).
+    runtimeOnly "com.fasterxml.jackson.core:jackson-core:${jackson2Version}"
+    runtimeOnly "com.fasterxml.jackson.core:jackson-databind:${jackson2Version}"
+
+    implementation("com.hubspot.jinjava:jinjava:${jinjavaVersion}") {
+        // Compile-time-only annotation artifacts (class-retention annotations, not needed at
+        // runtime) whose declared licences (LGPL / none) fail the licence compatibility check.
+        exclude group: 'com.google.code.findbugs', module: 'annotations'
+        exclude group: 'org.derive4j', module: 'derive4j-annotation'
+        exclude group: 'com.hubspot.immutables', module: 'hubspot-style'
+        exclude group: 'com.hubspot.immutables', module: 'immutable-collection-encodings'
+    }
+
     api 'io.micrometer:micrometer-registry-prometheus'
 
     api "io.jsonwebtoken:jjwt-api:${jwtVersion}"

app/proprietary/src/main/java/stirling/software/proprietary/controller/api/CreatePdfAgentController.java

@@ -8,12 +8,14 @@ import java.util.List;
 
 import org.apache.pdfbox.pdmodel.PDDocument;
 import org.springframework.core.io.Resource;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.server.ResponseStatusException;
 
 import io.github.pixee.security.Filenames;
 import io.swagger.v3.oas.annotations.Hidden;
@@ -24,18 +26,24 @@ import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 
 import stirling.software.common.configuration.RuntimePathConfig;
+import stirling.software.common.model.ApplicationProperties;
 import stirling.software.common.service.CustomPDFDocumentFactory;
 import stirling.software.common.util.ProcessExecutor;
 import stirling.software.common.util.TempFile;
 import stirling.software.common.util.TempFileManager;
 import stirling.software.common.util.WebResponseUtils;
+import stirling.software.proprietary.model.api.ai.create.AiDocument;
+import stirling.software.proprietary.service.AiDocumentHtmlRenderer;
+
+import tools.jackson.core.JacksonException;
+import tools.jackson.databind.ObjectMapper;
 
 /**
- * Dispatchable tool that converts an AI-generated HTML string to a PDF via WeasyPrint.
+ * Dispatchable tool that converts an AI-generated document model to a PDF via WeasyPrint.
  *
  * <p>Called by {@link stirling.software.proprietary.service.AiWorkflowService} when the engine
- * emits a {@code CREATE_PDF_FROM_HTML_AGENT} plan step. The HTML comes from a trusted Jinja
- * template so sanitization is intentionally skipped.
+ * emits a {@code CREATE_PDF_FROM_HTML_AGENT} plan step. The engine supplies the document as
+ * structured fields; the HTML is built here from a fixed template.
  */
 @Slf4j
 @Hidden
@@ -48,6 +56,9 @@ public class CreatePdfAgentController {
     private final TempFileManager tempFileManager;
     private final CustomPDFDocumentFactory pdfDocumentFactory;
     private final RuntimePathConfig runtimePathConfig;
+    private final ApplicationProperties applicationProperties;
+    private final ObjectMapper objectMapper;
+    private final AiDocumentHtmlRenderer htmlRenderer;
 
     /**
      * Returns true only when WeasyPrint is definitively unavailable — either the binary could not
@@ -74,32 +85,42 @@ public class CreatePdfAgentController {
             value = "/create-pdf-from-html-agent",
             consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
     @Operation(
-            summary = "Convert AI-generated HTML to a PDF",
+            summary = "Convert an AI-generated document to a PDF",
             description =
-                    "Accepts an HTML document as a plain-text parameter and returns a PDF."
-                            + " This endpoint is dispatched by the AI workflow orchestrator as a"
-                            + " plan step; it is not intended for direct client use.")
-    public ResponseEntity<Resource> createPdfFromHtml(
-            @RequestParam("htmlContent") String htmlContent,
-            @RequestParam("filename") String filename)
+                    "Accepts a structured document as a JSON parameter and returns a PDF. This"
+                            + " endpoint is dispatched by the AI workflow orchestrator as a plan"
+                            + " step; it is not intended for direct client use.")
+    public ResponseEntity<Resource> createPdf(
+            @RequestParam("document") String document, @RequestParam("filename") String filename)
             throws Exception {
 
+        if (!applicationProperties.getAiEngine().isEnabled()) {
+            throw new ResponseStatusException(HttpStatus.NOT_FOUND);
+        }
+
+        AiDocument model;
+        try {
+            model = objectMapper.readValue(document, AiDocument.class);
+        } catch (JacksonException e) {
+            throw new ResponseStatusException(HttpStatus.BAD_REQUEST);
+        }
+
+        String html = htmlRenderer.render(model);
+
         log.info(
-                "[create-pdf-agent] converting HTML to PDF via WeasyPrint — html_bytes={}",
-                htmlContent.length());
+                "[create-pdf-agent] converting document to PDF via WeasyPrint — html_bytes={}",
+                html.length());
 
         try (TempFile htmlFile = tempFileManager.createManagedTempFile(".html");
                 TempFile pdfFile = tempFileManager.createManagedTempFile(".pdf")) {
 
-            Files.writeString(htmlFile.getPath(), htmlContent, StandardCharsets.UTF_8);
+            Files.writeString(htmlFile.getPath(), html, StandardCharsets.UTF_8);
 
             List<String> command = new ArrayList<>();
             command.add(runtimePathConfig.getWeasyPrintPath());
             command.add("-e");
             command.add("utf-8");
             command.add("-v");
-            // SSRF: the HTML is self-contained and the engine validates style colours, so no
-            // external url() reaches WeasyPrint. For full isolation, run it network-isolated.
             command.add(htmlFile.getAbsolutePath());
             command.add(pdfFile.getAbsolutePath());
 
@@ -126,8 +147,8 @@ public class CreatePdfAgentController {
             // avoids materialising the whole document as a byte[] twice (read-all + re-serialise),
             // which matters for large generated documents.
             TempFile tempOut = tempFileManager.createManagedTempFile(".pdf");
-            try (PDDocument document = pdfDocumentFactory.load(pdfFile.getPath())) {
-                document.save(tempOut.getPath().toFile());
+            try (PDDocument pdDocument = pdfDocumentFactory.load(pdfFile.getPath())) {
+                pdDocument.save(tempOut.getPath().toFile());
             } catch (Exception e) {
                 tempOut.close();
                 throw e;

app/proprietary/src/main/java/stirling/software/proprietary/model/api/ai/create/AiDocument.java

@@ -0,0 +1,35 @@
+package stirling.software.proprietary.model.api.ai.create;
+
+import java.util.List;
+
+import lombok.Data;
+
+@Data
+public class AiDocument {
+
+    private String title;
+    private String subtitle;
+    private String referenceNumber;
+    private Style style;
+    private List<Section> sections;
+
+    @Data
+    public static class Style {
+        private String primaryColor;
+        private String backgroundColor;
+        private String bodyTextColor;
+    }
+
+    @Data
+    public static class Section {
+        private String type;
+        private String heading;
+        private String body;
+        private List<List<String>> pairs;
+        private List<String> columns;
+        private List<List<String>> rows;
+        private List<String> totalRow;
+        private List<String> items;
+        private List<String> signatories;
+    }
+}

app/proprietary/src/main/java/stirling/software/proprietary/service/AiDocumentHtmlRenderer.java

@@ -0,0 +1,135 @@
+package stirling.software.proprietary.service;
+
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.charset.StandardCharsets;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.stereotype.Component;
+
+import com.hubspot.jinjava.Jinjava;
+import com.hubspot.jinjava.JinjavaConfig;
+
+import stirling.software.proprietary.model.api.ai.create.AiDocument;
+
+/** Renders an {@link AiDocument} to HTML using a Jinja template loaded from the classpath. */
+@Component
+public class AiDocumentHtmlRenderer {
+
+    private static final String TEMPLATE_PATH = "templates/ai/create/document.html.jinja2";
+
+    private static final Pattern SAFE_COLOR = Pattern.compile("^#[0-9a-fA-F]{6}$");
+
+    private final Jinjava jinjava;
+    private final String template;
+
+    public AiDocumentHtmlRenderer() {
+        JinjavaConfig config =
+                JinjavaConfig.newBuilder().withNestedInterpretationEnabled(false).build();
+        this.jinjava = new Jinjava(config);
+        this.template = loadTemplate();
+    }
+
+    public String render(AiDocument doc) {
+        return jinjava.render(template, buildContext(doc));
+    }
+
+    private static Map<String, Object> buildContext(AiDocument doc) {
+        Map<String, Object> context = new LinkedHashMap<>();
+        context.put("title", doc.getTitle());
+        context.put("subtitle", doc.getSubtitle());
+        context.put("reference_number", doc.getReferenceNumber());
+
+        AiDocument.Style style = doc.getStyle();
+        if (style != null) {
+            context.put("style_primary", safeColor(style.getPrimaryColor()));
+            context.put("style_background", safeColor(style.getBackgroundColor()));
+            context.put("style_body", safeColor(style.getBodyTextColor()));
+        }
+
+        List<Map<String, Object>> sections = new ArrayList<>();
+        if (doc.getSections() != null) {
+            for (AiDocument.Section section : doc.getSections()) {
+                if (section != null && section.getType() != null) {
+                    sections.add(buildSection(section));
+                }
+            }
+        }
+        context.put("sections", sections);
+        return context;
+    }
+
+    private static Map<String, Object> buildSection(AiDocument.Section section) {
+        Map<String, Object> node = new LinkedHashMap<>();
+        node.put("type", section.getType());
+        node.put("heading", section.getHeading());
+        switch (section.getType()) {
+            case "text" -> node.put("paragraphs", paragraphs(section.getBody()));
+            case "key_value" -> node.put("pairs", pairs(section.getPairs()));
+            case "line_items" -> {
+                node.put("columns", orEmpty(section.getColumns()));
+                node.put("rows", orEmptyRows(section.getRows()));
+                node.put("total_row", emptyToNull(section.getTotalRow()));
+            }
+            case "bullet_list" -> node.put("items", orEmpty(section.getItems()));
+            case "signature" -> node.put("signatories", orEmpty(section.getSignatories()));
+            default -> {}
+        }
+        return node;
+    }
+
+    private static List<String> paragraphs(String body) {
+        String text = body == null ? "" : body;
+        List<String> out = new ArrayList<>();
+        for (String paragraph : text.split("\n\n")) {
+            out.add(paragraph.replace("\n", " "));
+        }
+        return out;
+    }
+
+    private static List<Map<String, String>> pairs(List<List<String>> pairs) {
+        List<Map<String, String>> out = new ArrayList<>();
+        if (pairs != null) {
+            for (List<String> pair : pairs) {
+                Map<String, String> node = new LinkedHashMap<>();
+                node.put("label", pair.isEmpty() ? "" : pair.get(0));
+                node.put("value", pair.size() < 2 ? "" : pair.get(1));
+                out.add(node);
+            }
+        }
+        return out;
+    }
+
+    private static List<String> orEmpty(List<String> values) {
+        return values == null ? List.of() : values;
+    }
+
+    private static List<List<String>> orEmptyRows(List<List<String>> rows) {
+        return rows == null ? List.of() : rows;
+    }
+
+    private static List<String> emptyToNull(List<String> values) {
+        return values == null || values.isEmpty() ? null : values;
+    }
+
+    private static String safeColor(String value) {
+        if (value == null) {
+            return null;
+        }
+        String trimmed = value.trim();
+        return SAFE_COLOR.matcher(trimmed).matches() ? trimmed : null;
+    }
+
+    private static String loadTemplate() {
+        try {
+            return new ClassPathResource(TEMPLATE_PATH).getContentAsString(StandardCharsets.UTF_8);
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        }
+    }
+}

app/proprietary/src/main/resources/templates/ai/create/document.html.jinja2

@@ -1,3 +1,4 @@
+{%- autoescape true -%}
 <!DOCTYPE html>
 <html lang="en">
 <head>
@@ -175,18 +176,18 @@
     color: var(--color-label);
   }
 </style>
-{%- if doc.style %}
+{%- if style_primary or style_background or style_body %}
 <style>
   :root {
-    {%- if doc.style.primary_color %}
-    --color-primary: {{ doc.style.primary_color }};
+    {%- if style_primary %}
+    --color-primary: {{ style_primary }};
     {%- endif %}
-    {%- if doc.style.background_color %}
-    --color-bg: {{ doc.style.background_color }};
+    {%- if style_background %}
+    --color-bg: {{ style_background }};
     {%- endif %}
-    {%- if doc.style.body_text_color %}
-    --color-body: {{ doc.style.body_text_color }};
-    --color-label: {{ doc.style.body_text_color }};
+    {%- if style_body %}
+    --color-body: {{ style_body }};
+    --color-label: {{ style_body }};
     {%- endif %}
   }
 </style>
@@ -195,16 +196,16 @@
 <body>
 
 <div class="doc-header">
-  <div class="doc-title">{{ doc.title }}</div>
-  {%- if doc.subtitle %}
-  <div class="doc-subtitle">{{ doc.subtitle }}</div>
+  <div class="doc-title">{{ title }}</div>
+  {%- if subtitle %}
+  <div class="doc-subtitle">{{ subtitle }}</div>
   {%- endif %}
-  {%- if doc.reference_number %}
-  <div class="doc-reference">{{ doc.reference_number }}</div>
+  {%- if reference_number %}
+  <div class="doc-reference">{{ reference_number }}</div>
   {%- endif %}
 </div>
 
-{%- for section in doc.sections %}
+{%- for section in sections %}
 
 {%- if section.type == "text" %}
 <section>
@@ -212,8 +213,8 @@
   <h2>{{ section.heading }}</h2>
   {%- endif %}
   <div class="text-body">
-    {%- for para in section.body.split('\n\n') %}
-    <p>{{ para | replace('\n', ' ') }}</p>
+    {%- for para in section.paragraphs %}
+    <p>{{ para }}</p>
     {%- endfor %}
   </div>
 </section>
@@ -225,10 +226,10 @@
   {%- endif %}
   <table class="kv-table">
     <tbody>
-      {%- for label, value in section.pairs %}
+      {%- for pair in section.pairs %}
       <tr>
-        <td class="kv-label">{{ label }}</td>
-        <td class="kv-value">{{ value }}</td>
+        <td class="kv-label">{{ pair.label }}</td>
+        <td class="kv-value">{{ pair.value }}</td>
       </tr>
       {%- endfor %}
     </tbody>
@@ -299,3 +300,4 @@
 
 </body>
 </html>
+{%- endautoescape %}

app/proprietary/src/test/java/stirling/software/proprietary/policy/engine/PolicyExecutorTest.java

@@ -166,8 +166,8 @@ class PolicyExecutorTest {
                                 new PipelineStep(
                                         createPdf,
                                         Map.of(
-                                                "htmlContent",
-                                                "<p>hi</p>",
+                                                "document",
+                                                "{\"title\":\"PO\",\"sections\":[]}",
                                                 "filename",
                                                 "purchase-order.pdf"))),
                         PolicyInputs.of(List.of()),

app/proprietary/src/test/java/stirling/software/proprietary/service/AiDocumentHtmlRendererTest.java

@@ -0,0 +1,139 @@
+package stirling.software.proprietary.service;
+
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+import stirling.software.proprietary.model.api.ai.create.AiDocument;
+
+class AiDocumentHtmlRendererTest {
+
+    private final AiDocumentHtmlRenderer renderer = new AiDocumentHtmlRenderer();
+
+    private static AiDocument.Section section(String type) {
+        AiDocument.Section s = new AiDocument.Section();
+        s.setType(type);
+        return s;
+    }
+
+    private static AiDocument document(String title, List<AiDocument.Section> sections) {
+        AiDocument doc = new AiDocument();
+        doc.setTitle(title);
+        doc.setSections(sections);
+        return doc;
+    }
+
+    @Test
+    void rendersAllSectionTypes() {
+        AiDocument.Section text = section("text");
+        text.setBody("Some prose text.");
+        AiDocument.Section kv = section("key_value");
+        kv.setPairs(List.of(List.of("Key", "Value")));
+        AiDocument.Section items = section("line_items");
+        items.setColumns(List.of("A", "B"));
+        items.setRows(List.of(List.of("1", "2")));
+        AiDocument.Section bullets = section("bullet_list");
+        bullets.setItems(List.of("item one"));
+        AiDocument.Section sign = section("signature");
+        sign.setSignatories(List.of("Alice"));
+
+        String html = renderer.render(document("All", List.of(text, kv, items, bullets, sign)));
+
+        assertTrue(html.contains("<!DOCTYPE html>"));
+        assertTrue(html.contains("Some prose text."));
+        assertTrue(html.contains("Key") && html.contains("Value"));
+        assertTrue(html.contains("<th>"));
+        assertTrue(html.contains("item one"));
+        assertTrue(html.contains("Alice"));
+    }
+
+    @Test
+    void rendersMarkupCharactersAsText() {
+        AiDocument.Section text = section("text");
+        text.setBody("a <b>x</b> & y");
+
+        String html = renderer.render(document("Doc", List.of(text)));
+
+        assertFalse(html.contains("<b>"));
+        assertTrue(html.contains("&lt;b&gt;"));
+    }
+
+    @Test
+    void totalRowRenderedWhenPresent() {
+        AiDocument.Section items = section("line_items");
+        items.setColumns(List.of("Item", "Total"));
+        items.setRows(List.of(List.of("Widget", "$10")));
+        items.setTotalRow(List.of("Total", "$10"));
+
+        assertTrue(
+                renderer.render(document("Table", List.of(items)))
+                        .contains("<tr class=\"total-row\">"));
+    }
+
+    @Test
+    void totalRowAbsentWhenNotProvided() {
+        AiDocument.Section items = section("line_items");
+        items.setColumns(List.of("Item"));
+        items.setRows(List.of(List.of("Widget")));
+
+        assertFalse(
+                renderer.render(document("Table", List.of(items)))
+                        .contains("<tr class=\"total-row\">"));
+    }
+
+    @Test
+    void rendersSubtitleAndReference() {
+        AiDocument doc = document("My Doc", List.of());
+        doc.setSubtitle("Subtitle Here");
+        doc.setReferenceNumber("REF-42");
+
+        String html = renderer.render(doc);
+
+        assertTrue(html.contains("Subtitle Here"));
+        assertTrue(html.contains("REF-42"));
+    }
+
+    @Test
+    void appliesHexColourOverride() {
+        AiDocument doc = document("Styled", List.of());
+        AiDocument.Style style = new AiDocument.Style();
+        style.setPrimaryColor("#ff00ff");
+        style.setBackgroundColor("#111111");
+        doc.setStyle(style);
+
+        String html = renderer.render(doc);
+
+        assertTrue(html.contains("--color-primary: #ff00ff"));
+        assertTrue(html.contains("--color-bg: #111111"));
+    }
+
+    @Test
+    void ignoresColourWithDisallowedCharacters() {
+        AiDocument doc = document("Styled", List.of());
+        AiDocument.Style style = new AiDocument.Style();
+        style.setPrimaryColor("rgb(255, 0, 0)");
+        doc.setStyle(style);
+
+        String html = renderer.render(doc);
+
+        assertFalse(html.contains("rgb("));
+        assertTrue(html.contains("<!DOCTYPE html>"));
+    }
+
+    @Test
+    void ignoresNonHexColour() {
+        AiDocument doc = document("Styled", List.of());
+        AiDocument.Style style = new AiDocument.Style();
+        style.setPrimaryColor("magenta");
+        style.setBackgroundColor("#fff");
+        doc.setStyle(style);
+
+        String html = renderer.render(doc);
+
+        assertFalse(html.contains("--color-primary: magenta"));
+        assertFalse(html.contains("--color-bg: #fff;"));
+    }
+}

build.gradle

@@ -36,6 +36,8 @@ ext {
     okhttpBomVersion = "5.3.2"
     gsonVersion = "2.14.0"
     guavaVersion = "33.6.0-jre"
+    jinjavaVersion = "2.8.3"
+    jackson2Version = "2.21.2"
     bucket4jVersion = "8.19.0"
     archunitVersion = "1.4.2"
     batikVersion = "1.19"
@@ -222,6 +224,13 @@ subprojects {
         resolutionStrategy.force "org.apache.commons:commons-lang3:${commonsLang3}"
         // CVE-2024-47554: commons-io DoS prevention
         resolutionStrategy.force "commons-io:commons-io:${commonsIoVersion}"
+        // Jackson 2 is transitive-only here (jinjava, opensaml, jjwt request older versions);
+        // pin the family to a current release and keep modules aligned.
+        resolutionStrategy.force "com.fasterxml.jackson.core:jackson-core:${jackson2Version}"
+        resolutionStrategy.force "com.fasterxml.jackson.core:jackson-databind:${jackson2Version}"
+        resolutionStrategy.force "com.fasterxml.jackson.dataformat:jackson-dataformat-yaml:${jackson2Version}"
+        resolutionStrategy.force "com.fasterxml.jackson.datatype:jackson-datatype-jdk8:${jackson2Version}"
+        resolutionStrategy.force "com.fasterxml.jackson.datatype:jackson-datatype-jsr310:${jackson2Version}"
         // Keep BouncyCastle modules aligned to avoid runtime linkage errors
         resolutionStrategy.force "org.bouncycastle:bcprov-jdk18on:${bouncycastleVersion}"
         resolutionStrategy.force "org.bouncycastle:bcpkix-jdk18on:${bouncycastleVersion}"

engine/pyproject.toml

@@ -5,7 +5,6 @@ description = "AI Document Engine"
 requires-python = ">=3.13"
 dependencies = [
     "fastapi>=0.116.0",
-    "jinja2>=3.1.0",
     "pgvector>=0.3.6",
     "psycopg[binary,pool]>=3.2",
     "pydantic>=2.0.0",

engine/src/stirling/agents/pdf_create/agent.py

@@ -10,7 +10,7 @@ Flow:
   4. SectionWriterAgents (smart_model) run in parallel via asyncio.gather.
      Each returns a WrittenSections with fully populated DocumentSection objects.
   5. The assembler collects sections in plan order → GeneratedDocument.
-  6. Jinja renders the document to HTML. The LLM never writes HTML.
+  6. The assembled document is emitted as structured fields. The LLM never writes HTML.
 
 The planner is split into two calls (meta then sections) so each LLM output schema
 stays small enough for grammar compilation on all model tiers including Haiku.
@@ -22,9 +22,7 @@ import asyncio
 import logging
 import re
 from dataclasses import dataclass
-from pathlib import Path
 
-from jinja2 import Environment, FileSystemLoader
 from pydantic_ai import Agent
 from pydantic_ai.output import NativeOutput
 
@@ -51,8 +49,6 @@ from stirling.services import AppRuntime
 
 logger = logging.getLogger(__name__)
 
-_TEMPLATES_DIR = Path(__file__).parent / "templates"
-
 # ── Token budget ──────────────────────────────────────────────────────────────────────────────────
 
 # Conservative per-section token estimates mapped from planner-assigned depth.
@@ -166,10 +162,13 @@ Analyse the user's request and produce a DocumentMeta with:
   document, if the user provides one. Leave empty if the user provides no such context.
 
 - style_primary_color: accent and heading colour. Set ONLY when the user explicitly names a
-  colour or colour scheme (e.g. "make it red", "use navy blue"). Use CSS named colours
-  (e.g. "magenta", "navy", "crimson") or hex values. Leave null if no colour is stated.
-- style_background_color: page background colour. Set only if explicitly requested.
-- style_body_text_color: body text colour. Set only if explicitly requested.
+  colour or colour scheme (e.g. "make it red", "use navy blue"). Express it as a 6-digit hex
+  code in #RRGGBB format (map any named colour to its hex value yourself, e.g. "navy" →
+  "#000080"). No other format is accepted. Leave null if no colour is stated.
+- style_background_color: page background colour, same #RRGGBB format. Set only if explicitly
+  requested.
+- style_body_text_color: body text colour, same #RRGGBB format. Set only if explicitly
+  requested.
 
 - cannot_do_reason: set this ONLY when the request is not asking to create a document at all
   (e.g. a question, a greeting, an edit request to an existing document). Never set it
@@ -299,15 +298,6 @@ def _build_writer_prompt(plan: DocumentPlan, chunk: _Chunk) -> str:
 # ── Helpers ───────────────────────────────────────────────────────────────────────────────────────
 
 
-def _build_jinja_env() -> Environment:
-    return Environment(
-        loader=FileSystemLoader(str(_TEMPLATES_DIR)),
-        autoescape=True,
-        trim_blocks=True,
-        lstrip_blocks=True,
-    )
-
-
 def _safe_filename(title: str) -> str:
     slug = re.sub(r"[^\w\s-]", "", title.lower())
     slug = re.sub(r"[\s_-]+", "-", slug).strip("-")
@@ -320,7 +310,6 @@ def _safe_filename(title: str) -> str:
 class PdfCreateAgent:
     def __init__(self, runtime: AppRuntime) -> None:
         self.runtime = runtime
-        self._jinja_env = _build_jinja_env()
 
         self._meta_planner: Agent[None, DocumentMeta] = Agent(
             model=runtime.smart_model,
@@ -401,14 +390,12 @@ class PdfCreateAgent:
             sections=all_sections,
         )
 
-        # ── Phase 6: render ────────────────────────────────────────────────────
-        logger.info("[pdf-create] phase 6/6: rendering HTML")
-        html = self._render(doc)
+        # ── Phase 6: emit ──────────────────────────────────────────────────────
         filename = _safe_filename(plan.title)
         logger.info(
-            "[pdf-create] done — filename=%r html_bytes=%d",
+            "[pdf-create] done — filename=%r sections=%d",
             filename,
-            len(html),
+            len(all_sections),
         )
 
         return EditPlanResponse(
@@ -417,7 +404,7 @@ class PdfCreateAgent:
                 ToolOperationStep(
                     tool=AgentToolId.CREATE_PDF_FROM_HTML_AGENT,
                     parameters=CreatePdfFromHtmlAgentParams(
-                        html_content=html,
+                        document=doc.model_dump_json(),
                         filename=filename,
                     ),
                 )
@@ -437,7 +424,3 @@ class PdfCreateAgent:
             len(result.output.sections),
         )
         return result.output
-
-    def _render(self, doc: GeneratedDocument) -> str:
-        template = self._jinja_env.get_template("document.html.jinja2")
-        return template.render(doc=doc)

engine/src/stirling/contracts/pdf_create.py

@@ -1,14 +1,14 @@
 """Contracts for the PDF Create Agent.
 
 The agent accepts a natural-language prompt and returns a single
-CREATE_PDF_FROM_HTML_AGENT plan step carrying the rendered HTML.
+CREATE_PDF_FROM_HTML_AGENT plan step carrying the assembled document.
 
 Pipeline:
   1. PlannerAgent (smart_model) → DocumentPlan: structured skeleton, no body text.
   2. Python chunks the plan by token budget.
   3. SectionWriterAgents (smart_model, parallel) → WrittenSections per chunk.
   4. Assembler collects sections in plan order → GeneratedDocument.
-  5. Jinja renders GeneratedDocument → HTML. The LLM never writes HTML.
+  5. The document is emitted as structured fields. The LLM never writes HTML.
 """
 
 from __future__ import annotations
@@ -81,14 +81,12 @@ type DocumentSection = Annotated[
 ]
 
 
-# Named colour or hex only — anything else is dropped so a colour can't inject CSS into the
-# <style> block (which would let WeasyPrint fetch an attacker-controlled url() → SSRF).
-_SAFE_COLOR_RE = re.compile(r"^#[0-9a-fA-F]{3,8}$|^[a-zA-Z]{1,30}$")
+# Colours must be a 6-digit hex code (#RRGGBB); anything else is dropped to None.
+_SAFE_COLOR_RE = re.compile(r"^#[0-9a-fA-F]{6}$")
 
 
 class DocumentStyle(ApiModel):
-    """Document colours, inferred by the meta planner and rendered into the engine's Jinja
-    template (never sent to Java). Unsafe colours are dropped to ``None``."""
+    """Document colours, inferred by the meta planner. Non-hex values are dropped to ``None``."""
 
     primary_color: str | None = Field(default=None)
     background_color: str | None = Field(default=None)
@@ -103,7 +101,7 @@ class DocumentStyle(ApiModel):
 
 
 class GeneratedDocument(ApiModel):
-    """The full document model passed to Jinja for HTML rendering."""
+    """The full document model emitted for rendering."""
 
     title: str
     subtitle: str | None = None

engine/src/stirling/models/agent_tool_models.py

@@ -29,7 +29,7 @@ class PdfCommentAgentParams(ApiModel):
 
 
 class CreatePdfFromHtmlAgentParams(ApiModel):
-    html_content: str
+    document: str
     filename: str = Field(pattern=r"^.+\.pdf$")
 
 

engine/tests/agents/test_pdf_create.py

@@ -2,7 +2,7 @@
 
 Coverage:
 1. Section model validation (each section type round-trips correctly)
-2. Jinja rendering (_render produces valid HTML for each section type)
+2. orchestrate() emits the assembled document as structured JSON
 3. _safe_filename produces clean slugs
 4. _make_chunks groups sections correctly by token budget
 5. orchestrate() produces the correct EditPlanResponse via planner + writer mocks
@@ -12,6 +12,8 @@ Coverage:
 
 from __future__ import annotations
 
+import json
+
 import pytest
 from conftest import build_app_settings
 from pydantic_ai.models.test import TestModel
@@ -64,37 +66,6 @@ def agent(runtime: AppRuntime) -> PdfCreateAgent:
 # ── Helpers ───────────────────────────────────────────────────────────────────────────────────────
 
 
-def _invoice_doc() -> GeneratedDocument:
-    return GeneratedDocument(
-        title="Invoice",
-        subtitle="Acme Corp",
-        reference_number="Invoice #INV-001",
-        sections=[
-            KeyValueSection(
-                heading="Details",
-                pairs=[("Date", "2026-05-06"), ("Due", "2026-06-06"), ("Currency", "USD")],
-            ),
-            LineItemsSection(
-                heading="Line Items",
-                columns=["Description", "Qty", "Unit Price", "Total"],
-                rows=[
-                    ["Consulting services", "10", "$500.00", "$5,000.00"],
-                    ["Expenses", "1", "$200.00", "$200.00"],
-                ],
-                total_row=["Total", "", "", "$5,200.00"],
-            ),
-            TextSection(
-                heading="Payment Terms",
-                body="Payment is due within 30 days.\n\nPlease reference the invoice number.",
-            ),
-            SignatureSection(
-                heading="Authorised By",
-                signatories=["Jane Smith, CEO", "Bob Jones, CFO"],
-            ),
-        ],
-    )
-
-
 def _simple_meta() -> DocumentMeta:
     return DocumentMeta(
         title="Invoice",
@@ -199,82 +170,6 @@ def test_generated_document_optional_fields() -> None:
     assert doc.reference_number is None
 
 
-# ── Jinja rendering ───────────────────────────────────────────────────────────────────────────────
-
-
-def test_render_produces_html(agent: PdfCreateAgent) -> None:
-    doc = _invoice_doc()
-    html = agent._render(doc)
-    assert "<!DOCTYPE html>" in html
-    assert "Invoice" in html
-    assert "INV-001" in html
-
-
-def test_render_includes_all_section_types(agent: PdfCreateAgent) -> None:
-    doc = GeneratedDocument(
-        title="All Sections",
-        sections=[
-            TextSection(body="Some prose text."),
-            KeyValueSection(pairs=[("Key", "Value")]),
-            LineItemsSection(columns=["A", "B"], rows=[["1", "2"]]),
-            BulletListSection(items=["item one"]),
-            SignatureSection(signatories=["Alice"]),
-        ],
-    )
-    html = agent._render(doc)
-    assert "Some prose text." in html
-    assert "Key" in html and "Value" in html
-    assert "<th>" in html
-    assert "item one" in html
-    assert "Alice" in html
-
-
-def test_render_escapes_html_in_content(agent: PdfCreateAgent) -> None:
-    doc = GeneratedDocument(
-        title="XSS Test",
-        sections=[TextSection(body="<script>alert('xss')</script>")],
-    )
-    html = agent._render(doc)
-    assert "<script>" not in html
-    assert "&lt;script&gt;" in html
-
-
-def test_render_total_row_present(agent: PdfCreateAgent) -> None:
-    doc = GeneratedDocument(
-        title="Table",
-        sections=[
-            LineItemsSection(
-                columns=["Item", "Total"],
-                rows=[["Widget", "$10"]],
-                total_row=["Total", "$10"],
-            )
-        ],
-    )
-    html = agent._render(doc)
-    assert "total-row" in html
-
-
-def test_render_no_total_row_skips_tfoot(agent: PdfCreateAgent) -> None:
-    doc = GeneratedDocument(
-        title="Table",
-        sections=[LineItemsSection(columns=["Item"], rows=[["Widget"]])],
-    )
-    html = agent._render(doc)
-    assert "<tfoot>" not in html
-
-
-def test_render_subtitle_and_reference(agent: PdfCreateAgent) -> None:
-    doc = GeneratedDocument(
-        title="My Doc",
-        subtitle="Subtitle Here",
-        reference_number="REF-42",
-        sections=[TextSection(body="Content.")],
-    )
-    html = agent._render(doc)
-    assert "Subtitle Here" in html
-    assert "REF-42" in html
-
-
 # ── _safe_filename ────────────────────────────────────────────────────────────────────────────────
 
 
@@ -396,8 +291,9 @@ async def test_orchestrate_returns_plan_step(agent: PdfCreateAgent) -> None:
     assert step.tool == AgentToolId.CREATE_PDF_FROM_HTML_AGENT
     assert isinstance(step.parameters, CreatePdfFromHtmlAgentParams)
     assert step.parameters.filename.endswith(".pdf")
-    assert "<!DOCTYPE html>" in step.parameters.html_content
-    assert "Invoice" in step.parameters.html_content
+    parsed = json.loads(step.parameters.document)
+    assert parsed["title"] == "Invoice"
+    assert parsed["sections"]
 
 
 @pytest.mark.anyio
@@ -468,9 +364,9 @@ async def test_orchestrate_assembles_multiple_chunks(agent: PdfCreateAgent) -> N
         result = await agent.orchestrate(_orchestrator_request("Create a multi-chunk doc"))
 
     assert isinstance(result, EditPlanResponse)
-    html = result.steps[0].parameters.html_content  # type: ignore[union-attr]
-    assert "Introduction text." in html
-    assert "Details" in html
+    document = result.steps[0].parameters.document  # type: ignore[union-attr]
+    assert "Introduction text." in document
+    assert "Details" in document
 
 
 # ── Style inference ───────────────────────────────────────────────────────────────────────────────
@@ -482,7 +378,7 @@ async def test_orchestrate_applies_planner_inferred_style(agent: PdfCreateAgent)
     meta = DocumentMeta(
         title="Styled Doc",
         tone_brief="Professional.",
-        style_primary_color="magenta",
+        style_primary_color="#ff00ff",
     )
     sections = _simple_sections()
     written = _written_sections()
@@ -499,50 +395,35 @@ async def test_orchestrate_applies_planner_inferred_style(agent: PdfCreateAgent)
         result = await agent.orchestrate(_orchestrator_request("Make an invoice, magenta styling"))
 
     assert isinstance(result, EditPlanResponse)
-    html = result.steps[0].parameters.html_content  # type: ignore[union-attr]
-    assert "magenta" in html
+    document = result.steps[0].parameters.document  # type: ignore[union-attr]
+    assert json.loads(document)["style"]["primaryColor"] == "#ff00ff"
 
 
-def test_render_applies_style(agent: PdfCreateAgent) -> None:
-    """DocumentStyle fields are injected as CSS custom properties in the rendered HTML."""
-    doc = GeneratedDocument(
-        title="Styled",
-        sections=[TextSection(body="Content.")],
-        style=DocumentStyle(primary_color="magenta", background_color="#111111"),
-    )
-    html = agent._render(doc)
-    assert "--color-primary: magenta" in html
-    assert "--color-bg: #111111" in html
-
-
-def test_document_style_drops_unsafe_colors() -> None:
-    """Unsafe colours (not named/hex) are dropped, closing the <style> url() injection."""
-    safe = DocumentStyle(primary_color="navy", background_color="#1e3a5f", body_text_color="#fff")
+def test_document_style_keeps_only_six_digit_hex() -> None:
+    """Only #RRGGBB hex is kept; named colours and other formats drop to None."""
+    safe = DocumentStyle(primary_color="#1e3a5f", background_color="#ffffff", body_text_color="#1A1A1A")
     assert (safe.primary_color, safe.background_color, safe.body_text_color) == (
-        "navy",
         "#1e3a5f",
-        "#fff",
+        "#ffffff",
+        "#1A1A1A",
     )
 
-    unsafe = DocumentStyle(
-        primary_color="red; background: url(http://evil.test/steal)",
-        background_color="expression(alert(1))",
-        body_text_color="navy; }",
-    )
-    assert unsafe.primary_color is None
-    assert unsafe.background_color is None
-    assert unsafe.body_text_color is None
+    assert DocumentStyle(primary_color="navy").primary_color is None
+    assert DocumentStyle(primary_color="#fff").primary_color is None
+    assert DocumentStyle(primary_color="#1e3a5f00").primary_color is None
+    assert DocumentStyle(primary_color="rgb(255, 0, 0)").primary_color is None
+    assert DocumentStyle(background_color="teal darken-2").background_color is None
     # A trailing newline must not slip a value through (fullmatch, not $-before-newline).
-    assert DocumentStyle(primary_color="navy\n").primary_color is None
+    assert DocumentStyle(primary_color="#1e3a5f\n").primary_color is None
 
 
 @pytest.mark.anyio
-async def test_orchestrate_drops_unsafe_planner_color(agent: PdfCreateAgent) -> None:
-    """An unsafe colour inferred by the meta planner never reaches the rendered HTML."""
+async def test_orchestrate_drops_non_hex_planner_colour(agent: PdfCreateAgent) -> None:
+    """A non-hex colour inferred by the meta planner is dropped before the document is emitted."""
     meta = DocumentMeta(
         title="Doc",
         tone_brief="Professional.",
-        style_primary_color="blue; background: url(http://evil.test/)",
+        style_primary_color="rgb(0, 0, 255)",
     )
     sections = _simple_sections()
     written = _written_sections()
@@ -559,6 +440,6 @@ async def test_orchestrate_drops_unsafe_planner_color(agent: PdfCreateAgent) ->
         result = await agent.orchestrate(_orchestrator_request("make it blue"))
 
     assert isinstance(result, EditPlanResponse)
-    html = result.steps[0].parameters.html_content  # type: ignore[union-attr]
-    assert "evil.test" not in html
-    assert "url(" not in html
+    document = result.steps[0].parameters.document  # type: ignore[union-attr]
+    assert "rgb(" not in document
+    assert json.loads(document)["style"]["primaryColor"] is None

engine/uv.lock

@@ -604,7 +604,6 @@ version = "0.1.0"
 source = { editable = "." }
 dependencies = [
     { name = "fastapi" },
-    { name = "jinja2" },
     { name = "opentelemetry-sdk" },
     { name = "pgvector" },
     { name = "posthog" },
@@ -631,7 +630,6 @@ dev = [
 [package.metadata]
 requires-dist = [
     { name = "fastapi", specifier = ">=0.116.0" },
-    { name = "jinja2", specifier = ">=3.1.0" },
     { name = "opentelemetry-sdk", specifier = ">=1.39.0" },
     { name = "pgvector", specifier = ">=0.3.6" },
     { name = "posthog", specifier = ">=3.0.0" },