Add image-gen module: Spring AI ImageModel options on the wire, a moderation gate, and safe storage of generated images in MinIO (sniffed content type, byte and pixel caps, server-chosen keys, capped URL fetcher); per-provider cost table dated 2026-10-28. ImageModel and ModerationModel are hand-written fakes; MinIO is real via Testcontainers; no image provider called.

Co-Authored-By: Claude Sonnet 5.5 <[email protected]> Claude-Session: https://claude.ai/code/session_017ic4b7rnC7jppGGdHGESvy
2026-10-28 18:36:40 +00:00
parent 108fc44542
commit aa8b1604ed
48 changed files with 2112 additions and 0 deletions
@@ -0,0 +1,65 @@
+package com.ankurm.imagegen;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.ai.moderation.Categories;
+import org.springframework.ai.moderation.ModerationModel;
+import org.springframework.ai.moderation.ModerationPrompt;
+import org.springframework.ai.moderation.ModerationResult;
+
+/**
+ * The moderation step Spring AI does not run for you. It asks a {@link ModerationModel} about the
+ * prompt before any image is requested and fails closed: if the moderation call itself throws, the
+ * prompt is refused rather than waved through.
+ *
+ * <p>This inspects the TEXT. It says nothing about the picture that comes back.
+ */
+public final class PromptGate {
+
+    private final ModerationModel moderation;
+    private final ImagePolicy policy;
+
+    public PromptGate(ModerationModel moderation, ImagePolicy policy) {
+        this.moderation = moderation;
+        this.policy = policy;
+    }
+
+    public void check(String prompt) {
+        if (prompt == null || prompt.isBlank()) {
+            throw new RejectedException("empty-prompt", "prompt is blank");
+        }
+        if (prompt.length() > policy.maxPromptChars()) {
+            throw new RejectedException("prompt-too-long", prompt.length() + " > " + policy.maxPromptChars());
+        }
+        if (prompt.chars().anyMatch(c -> Character.isISOControl(c) && c != '\n' && c != '\t')) {
+            throw new RejectedException("control-characters", "prompt contains control characters");
+        }
+        List<String> flagged = new ArrayList<>();
+        try {
+            for (ModerationResult r : moderation.call(new ModerationPrompt(prompt)).getResult().getOutput().getResults()) {
+                if (r.isFlagged()) {
+                    flagged.addAll(flaggedCategories(r.getCategories()));
+                }
+            }
+        } catch (RuntimeException e) {
+            throw new RejectedException("moderation-unavailable", e.getClass().getSimpleName());
+        }
+        if (!flagged.isEmpty()) {
+            throw new RejectedException("prompt-flagged", String.join(",", flagged));
+        }
+    }
+
+    private static List<String> flaggedCategories(Categories c) {
+        List<String> out = new ArrayList<>();
+        if (c == null) return List.of("unspecified");
+        if (c.isSexual()) out.add("sexual");
+        if (c.isSexualMinors()) out.add("sexual/minors");
+        if (c.isHate()) out.add("hate");
+        if (c.isHarassment()) out.add("harassment");
+        if (c.isSelfHarm()) out.add("self-harm");
+        if (c.isViolence()) out.add("violence");
+        if (c.isViolenceGraphic()) out.add("violence/graphic");
+        return out.isEmpty() ? List.of("unspecified") : out;
+    }
+}