Allow Mastodon to Quote Post

src/main/java/net/javahippie/fitpub/controller/ActivityPubController.java

@@ -426,9 +426,13 @@ public class ActivityPubController {
         String actorUri = baseUrl + "/users/" + user.getUsername();
         String activityUri = baseUrl + "/activities/" + activity.getId();
 
-        // Build the Note object (same format as used in federation)
+        // Build the Note object (same format as used in federation).
+        // The extended JSON-LD context declares Mastodon's interaction-policy
+        // extension fields so the `interactionPolicy` field below is parsed
+        // by Mastodon receivers (otherwise they fall back to denying quotes
+        // for cross-server posts).
         Map<String, Object> noteObject = new HashMap<>();
-        noteObject.put("@context", "https://www.w3.org/ns/activitystreams");
+        noteObject.put("@context", net.javahippie.fitpub.util.ActivityPubContexts.extendedContext());
         noteObject.put("id", activityUri);
         noteObject.put("type", "Note");
         noteObject.put("attributedTo", actorUri);
@@ -436,10 +440,17 @@ public class ActivityPubController {
         noteObject.put("content", formatActivityContent(activity));
         noteObject.put("url", activityUri);
 
-        // Audience
+        // Audience — only PUBLIC activities reach this endpoint (the visibility
+        // check above returned 403 for anything else), so audience is always
+        // the AS Public collection.
         noteObject.put("to", List.of("https://www.w3.org/ns/activitystreams#Public"));
         noteObject.put("cc", List.of(actorUri + "/followers"));
 
+        // Allow public quotes (matches the audience).
+        noteObject.put("interactionPolicy",
+            net.javahippie.fitpub.util.ActivityPubContexts.quotePolicyAllowing(
+                "https://www.w3.org/ns/activitystreams#Public"));
+
         // Extract hashtags from user text and add as tags
         List<String> hashtags = extractHashtags(activity);
         if (!hashtags.isEmpty()) {
@@ -489,49 +500,74 @@ public class ActivityPubController {
      * Format activity content as HTML for ActivityPub.
      * Mastodon and most Fediverse software expect HTML in the content field.
      */
+    /**
+     * Format activity content as HTML for the ActivityPub Note. Output is
+     * intentionally minimal because the bulk of the activity data is already
+     * in the share image attachment (and its alt text). The body provides:
+     * the title (bold), a one-line context summary as a fallback for clients
+     * that don't render image attachments, and the user-written description
+     * (with hashtags linkified).
+     */
     private String formatActivityContent(Activity activity) {
         StringBuilder content = new StringBuilder();
 
         if (activity.getTitle() != null && !activity.getTitle().isEmpty()) {
-            content.append("<p><strong>").append(linkifyHashtags(escapeHtml(activity.getTitle()))).append("</strong></p>");
+            content.append("<p><strong>")
+                   .append(linkifyHashtags(escapeHtml(activity.getTitle())))
+                   .append("</strong></p>");
+        }
+
+        // One-line summary (sport · distance · duration). Fallback for clients
+        // that don't show the image attachment, and a quick at-a-glance line
+        // even for clients that do.
+        String summary = buildSummaryLine(activity);
+        if (!summary.isEmpty()) {
+            content.append("<p>").append(summary).append("</p>");
         }
 
         if (activity.getDescription() != null && !activity.getDescription().isEmpty()) {
-            content.append("<p>").append(linkifyHashtags(escapeHtml(activity.getDescription()))).append("</p>");
+            content.append("<p>")
-        }
+                   .append(linkifyHashtags(escapeHtml(activity.getDescription())))
-
+                   .append("</p>");
-        String activityEmoji = getActivityEmoji(activity.getActivityType());
-        String formattedType = ActivityFormatter.formatActivityType(activity.getActivityType());
-        content.append("<p>").append(activityEmoji).append(" ").append(escapeHtml(formattedType)).append("</p>");
-
-        StringBuilder metrics = new StringBuilder();
-        if (activity.getTotalDistance() != null) {
-            metrics.append("📏 ")
-                .append(String.format("%.2f km", activity.getTotalDistance().doubleValue() / 1000.0))
-                .append("<br>");
-        }
-        if (activity.getTotalDurationSeconds() != null) {
-            long hours = activity.getTotalDurationSeconds() / 3600;
-            long minutes = (activity.getTotalDurationSeconds() % 3600) / 60;
-            long seconds = activity.getTotalDurationSeconds() % 60;
-            metrics.append("⏱️ ");
-            if (hours > 0) {
-                metrics.append(hours).append("h ");
-            }
-            metrics.append(minutes).append("m ").append(seconds).append("s").append("<br>");
-        }
-        if (activity.getElevationGain() != null) {
-            metrics.append("⛰️ ")
-                .append(String.format("%.0f m", activity.getElevationGain().doubleValue()))
-                .append("<br>");
-        }
-        if (metrics.length() > 0) {
-            content.append("<p>").append(metrics).append("</p>");
         }
 
         return content.toString();
     }
 
+    /**
+     * Build a one-line plain summary like "Run · 6.52 km · 43:30". Skips any
+     * field that's null or zero so indoor activities (no distance) just show
+     * "Indoor cycling · 45:12". Returns "" if absolutely nothing is available.
+     */
+    private String buildSummaryLine(Activity activity) {
+        java.util.List<String> parts = new java.util.ArrayList<>();
+
+        String type = ActivityFormatter.formatActivityType(activity.getActivityType());
+        if (type != null && !type.isEmpty()) {
+            parts.add(escapeHtml(type));
+        }
+
+        if (activity.getTotalDistance() != null
+            && activity.getTotalDistance().doubleValue() > 0) {
+            parts.add(String.format("%.2f km", activity.getTotalDistance().doubleValue() / 1000.0));
+        }
+
+        if (activity.getTotalDurationSeconds() != null
+            && activity.getTotalDurationSeconds() > 0) {
+            long s = activity.getTotalDurationSeconds();
+            long h = s / 3600;
+            long m = (s % 3600) / 60;
+            long sec = s % 60;
+            if (h > 0) {
+                parts.add(String.format("%d:%02d:%02d", h, m, sec));
+            } else {
+                parts.add(String.format("%d:%02d", m, sec));
+            }
+        }
+
+        return String.join(" · ", parts);
+    }
+
     private static final java.util.regex.Pattern HASHTAG_PATTERN =
         java.util.regex.Pattern.compile("(?<=^|\\s)#(\\w+)", java.util.regex.Pattern.UNICODE_CHARACTER_CLASS);
 
@@ -567,14 +603,4 @@ public class ActivityPubController {
                    .replace("\"", "&quot;");
     }
 
-    private String getActivityEmoji(Activity.ActivityType activityType) {
-        return switch (activityType) {
-            case RUN -> "🏃";
-            case RIDE -> "🚴";
-            case HIKE -> "🥾";
-            case WALK -> "🚶";
-            case SWIM -> "🏊";
-            default -> "💪";
-        };
-    }
 }

src/main/java/net/javahippie/fitpub/service/ActivityPostProcessingService.java

@@ -219,14 +219,26 @@ public class ActivityPostProcessingService {
             }
 
             // Set visibility (to/cc fields)
+            String quoteAudience;
             if (activity.getVisibility() == Activity.Visibility.PUBLIC) {
                 noteObject.put("to", List.of("https://www.w3.org/ns/activitystreams#Public"));
                 noteObject.put("cc", List.of(actorUri + "/followers"));
+                quoteAudience = "https://www.w3.org/ns/activitystreams#Public";
             } else {
                 // FOLLOWERS only
                 noteObject.put("to", List.of(actorUri + "/followers"));
+                quoteAudience = actorUri + "/followers";
             }
 
+            // Tell Mastodon (and other servers that implement FEP-5e53) that
+            // this post can be quoted by the same audience that can see it.
+            // Without this declaration Mastodon defaults to denying quotes
+            // for cross-server posts, which surfaces as `quote_approval.current_user
+            // == "denied"` in its API. The matching extension field declarations
+            // live on the surrounding Create's `@context` (set by FederationService).
+            noteObject.put("interactionPolicy",
+                net.javahippie.fitpub.util.ActivityPubContexts.quotePolicyAllowing(quoteAudience));
+
             // Attach activity image if generated
             if (imageUrl != null) {
                 Map<String, Object> imageAttachment = new HashMap<>();
@@ -259,53 +271,73 @@ public class ActivityPostProcessingService {
     }
 
     /**
-     * Format activity content as HTML for ActivityPub Note.
+     * Format activity content as HTML for the ActivityPub Note. Output is
-     * Mastodon and most Fediverse software expect HTML in the content field.
+     * intentionally minimal because the bulk of the activity data is already
-     * Hashtags in user text are converted to proper HTML links.
+     * in the share image attachment (and its alt text). The body provides:
+     * the title (bold), a one-line context summary as a fallback for clients
+     * that don't render image attachments, and the user-written description
+     * (with hashtags linkified).
      */
     private String formatActivityContent(Activity activity) {
         StringBuilder content = new StringBuilder();
 
         if (activity.getTitle() != null && !activity.getTitle().isEmpty()) {
-            content.append("<p><strong>").append(linkifyHashtags(escapeHtml(activity.getTitle()))).append("</strong></p>");
+            content.append("<p><strong>")
+                   .append(linkifyHashtags(escapeHtml(activity.getTitle())))
+                   .append("</strong></p>");
+        }
+
+        // One-line summary (sport · distance · duration). Fallback for clients
+        // that don't render the image attachment, and a quick at-a-glance line
+        // even for clients that do.
+        String summary = buildSummaryLine(activity);
+        if (!summary.isEmpty()) {
+            content.append("<p>").append(summary).append("</p>");
         }
 
         if (activity.getDescription() != null && !activity.getDescription().isEmpty()) {
-            content.append("<p>").append(linkifyHashtags(escapeHtml(activity.getDescription()))).append("</p>");
+            content.append("<p>")
-        }
+                   .append(linkifyHashtags(escapeHtml(activity.getDescription())))
-
+                   .append("</p>");
-        String activityEmoji = getActivityEmoji(activity.getActivityType());
-        String formattedType = ActivityFormatter.formatActivityType(activity.getActivityType());
-        content.append("<p>").append(activityEmoji).append(" ").append(escapeHtml(formattedType)).append("</p>");
-
-        StringBuilder metrics = new StringBuilder();
-        if (activity.getTotalDistance() != null) {
-            metrics.append("📏 ")
-                .append(String.format("%.2f km", activity.getTotalDistance().doubleValue() / 1000.0))
-                .append("<br>");
-        }
-        if (activity.getTotalDurationSeconds() != null) {
-            long hours = activity.getTotalDurationSeconds() / 3600;
-            long minutes = (activity.getTotalDurationSeconds() % 3600) / 60;
-            long seconds = activity.getTotalDurationSeconds() % 60;
-            metrics.append("⏱️ ");
-            if (hours > 0) {
-                metrics.append(hours).append("h ");
-            }
-            metrics.append(minutes).append("m ").append(seconds).append("s").append("<br>");
-        }
-        if (activity.getElevationGain() != null) {
-            metrics.append("⛰️ ")
-                .append(String.format("%.0f m", activity.getElevationGain()))
-                .append("<br>");
-        }
-        if (metrics.length() > 0) {
-            content.append("<p>").append(metrics).append("</p>");
         }
 
         return content.toString();
     }
 
+    /**
+     * Build a one-line plain summary like "Run · 6.52 km · 43:30". Skips any
+     * field that's null or zero so indoor activities (no distance) just show
+     * "Indoor cycling · 45:12". Returns "" if absolutely nothing is available.
+     */
+    private String buildSummaryLine(Activity activity) {
+        java.util.List<String> parts = new java.util.ArrayList<>();
+
+        String type = ActivityFormatter.formatActivityType(activity.getActivityType());
+        if (type != null && !type.isEmpty()) {
+            parts.add(escapeHtml(type));
+        }
+
+        if (activity.getTotalDistance() != null
+            && activity.getTotalDistance().doubleValue() > 0) {
+            parts.add(String.format("%.2f km", activity.getTotalDistance().doubleValue() / 1000.0));
+        }
+
+        if (activity.getTotalDurationSeconds() != null
+            && activity.getTotalDurationSeconds() > 0) {
+            long s = activity.getTotalDurationSeconds();
+            long h = s / 3600;
+            long m = (s % 3600) / 60;
+            long sec = s % 60;
+            if (h > 0) {
+                parts.add(String.format("%d:%02d:%02d", h, m, sec));
+            } else {
+                parts.add(String.format("%d:%02d", m, sec));
+            }
+        }
+
+        return String.join(" · ", parts);
+    }
+
     private static final java.util.regex.Pattern HASHTAG_PATTERN =
         java.util.regex.Pattern.compile("(?<=^|\\s)#(\\w+)", java.util.regex.Pattern.UNICODE_CHARACTER_CLASS);
 
@@ -347,28 +379,4 @@ public class ActivityPostProcessingService {
                    .replace("\"", "&quot;");
     }
 
-    /**
-     * Get an emoji for the activity type.
-     *
-     * @param type the activity type
-     * @return emoji representing the activity type
-     */
-    private String getActivityEmoji(Activity.ActivityType type) {
-        return switch (type) {
-            case RUN -> "🏃";
-            case RIDE -> "🚴";
-            case HIKE -> "🥾";
-            case WALK -> "🚶";
-            case SWIM -> "🏊";
-            case ALPINE_SKI, BACKCOUNTRY_SKI, NORDIC_SKI -> "⛷️";
-            case SNOWBOARD -> "🏂";
-            case ROWING -> "🚣";
-            case KAYAKING, CANOEING -> "🛶";
-            case INLINE_SKATING -> "⛸️";
-            case ROCK_CLIMBING, MOUNTAINEERING -> "🧗";
-            case YOGA -> "🧘";
-            case WORKOUT -> "💪";
-            default -> "🏋️";
-        };
-    }
 }

src/main/java/net/javahippie/fitpub/service/FederationService.java

@@ -369,7 +369,12 @@ public class FederationService {
             String actorUri = baseUrl + "/users/" + sender.getUsername();
 
             Map<String, Object> createActivity = new HashMap<>();
-            createActivity.put("@context", "https://www.w3.org/ns/activitystreams");
+            // Use the extended JSON-LD context that declares Mastodon's
+            // interaction-policy extension fields. This is needed so that
+            // any inner object carrying an `interactionPolicy` (e.g. Notes
+            // emitted by ActivityPostProcessingService that allow quotes)
+            // is correctly understood by Mastodon's parser.
+            createActivity.put("@context", net.javahippie.fitpub.util.ActivityPubContexts.extendedContext());
             createActivity.put("type", "Create");
             createActivity.put("id", createId);
             createActivity.put("actor", actorUri);

src/main/java/net/javahippie/fitpub/util/ActivityPubContexts.java

@@ -0,0 +1,101 @@
+package net.javahippie.fitpub.util;
+
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Shared {@code @context} builders for outbound ActivityPub objects.
+ *
+ * <p>Centralises the JSON-LD context shape so all the federation code paths
+ * (Create wrappers in {@code FederationService}, the standalone Note returned
+ * by {@code ActivityPubController#getActivity}) use the same one.
+ *
+ * <p>The "extended" context declares the interaction-policy extension fields
+ * ({@code interactionPolicy}, {@code canQuote}, {@code automaticApproval},
+ * {@code manualApproval}) under the {@code gts:} prefix
+ * ({@code https://gotosocial.org/ns#}). This matches Mastodon's
+ * {@code app/helpers/context_helper.rb} ("interaction_policies" extension),
+ * which declares these fields in the GoToSocial namespace rather than
+ * Mastodon's own {@code toot:} namespace. Without these declarations,
+ * Mastodon ignores any {@code interactionPolicy} field on the inner object
+ * and falls back to its default policy (which currently denies quotes for
+ * cross-server posts).
+ *
+ * <p>This file deliberately doesn't try to enumerate every possible Mastodon
+ * extension — only the ones we actively use. Add fields here as we adopt them.
+ */
+public final class ActivityPubContexts {
+
+    /** The well-known ActivityStreams "Public" audience URI. */
+    public static final String PUBLIC_AUDIENCE = "https://www.w3.org/ns/activitystreams#Public";
+
+    private ActivityPubContexts() {
+    }
+
+    /**
+     * Returns the extended JSON-LD {@code @context} value for outbound objects
+     * that carry interaction-policy declarations. Shape:
+     *
+     * <pre>
+     * [
+     *   "https://www.w3.org/ns/activitystreams",
+     *   {
+     *     "gts": "https://gotosocial.org/ns#",
+     *     "interactionPolicy":  { "@id": "gts:interactionPolicy",  "@type": "@id" },
+     *     "canQuote":           { "@id": "gts:canQuote",           "@type": "@id" },
+     *     "automaticApproval":  { "@id": "gts:automaticApproval",  "@type": "@id" },
+     *     "manualApproval":     { "@id": "gts:manualApproval",     "@type": "@id" }
+     *   }
+     * ]
+     * </pre>
+     *
+     * <p>The {@code gts:} prefix is the GoToSocial namespace
+     * ({@code https://gotosocial.org/ns#}). Mastodon emits and consumes
+     * exactly this shape (see {@code app/helpers/context_helper.rb} in the
+     * Mastodon source, "interaction_policies" extension), so a Mastodon
+     * receiver compacting our object with its own context will recognise the
+     * field names and apply the policy.
+     */
+    public static List<Object> extendedContext() {
+        Map<String, Object> extensions = new LinkedHashMap<>();
+        extensions.put("gts", "https://gotosocial.org/ns#");
+        extensions.put("interactionPolicy", typedRef("gts:interactionPolicy"));
+        extensions.put("canQuote",          typedRef("gts:canQuote"));
+        extensions.put("automaticApproval", typedRef("gts:automaticApproval"));
+        extensions.put("manualApproval",    typedRef("gts:manualApproval"));
+        return List.of(
+            "https://www.w3.org/ns/activitystreams",
+            extensions
+        );
+    }
+
+    /**
+     * Build an interaction policy that allows the given audience to quote
+     * automatically (no manual approval required). The audience should be a
+     * URI like {@link #PUBLIC_AUDIENCE} or an actor's followers collection.
+     *
+     * <p>Shape:
+     * <pre>
+     * {
+     *   "canQuote": {
+     *     "automaticApproval": ["https://www.w3.org/ns/activitystreams#Public"]
+     *   }
+     * }
+     * </pre>
+     */
+    public static Map<String, Object> quotePolicyAllowing(String audienceUri) {
+        Map<String, Object> canQuote = new LinkedHashMap<>();
+        canQuote.put("automaticApproval", List.of(audienceUri));
+        Map<String, Object> policy = new LinkedHashMap<>();
+        policy.put("canQuote", canQuote);
+        return policy;
+    }
+
+    private static Map<String, String> typedRef(String id) {
+        Map<String, String> m = new LinkedHashMap<>();
+        m.put("@id", id);
+        m.put("@type", "@id");
+        return m;
+    }
+}