feat!: mint file links at click time, and voice fixes for late interruptions

config/example.yaml

@@ -194,9 +194,7 @@ tools:
   - { id: search, kind: builtin, uses: web.search }
 
   # kind: builtin, a plain function. The model calls it when a file in the conversation's workspace is a
-  # deliverable: the file is copied into providers.blobs (see 8. providers), owned by the conversation,
-  # and the person gets a link. Files not published are lost when the conversation ends. Needs
-  # providers.blobs and options.UseWorkspace(...) on the host; missing either fails the boot.
+  # deliverable: the file is copied into providers.blobs.
   - { id: publish, kind: builtin, uses: file.publish }
 
   # kind: binding, typed form. Not used in this example. The host registered

src/AgentCore.Application/Blobs/BlobLink.cs

@@ -4,7 +4,7 @@ namespace AgentCore.Application.Blobs
     public static class BlobLink
     {
         /// <summary>How long a link works.</summary>
-        public static TimeSpan Lifetime { get; } = TimeSpan.FromMinutes(15);
+        public static TimeSpan Lifetime { get; } = TimeSpan.FromMinutes(5);
 
         /// <summary>
         /// The <c>Content-Disposition</c> a link serves the blob with: <c>inline</c> for what a browser

src/AgentCore.Application/Blobs/BlobOwner.cs

@@ -0,0 +1,16 @@
+namespace AgentCore.Application.Blobs
+{
+    /// <summary>
+    /// The one shape a blob owner id may take. An owner id is the first segment of a key, never a path.
+    /// </summary>
+    public static class BlobOwner
+    {
+        /// <summary>Says whether an owner id is safe to use as the first segment of a key.</summary>
+        /// <param name="ownerId">The conversation id or other owner the caller wrote.</param>
+        /// <returns><see langword="true"/> when the id is not blank and holds no slash.</returns>
+        public static bool IsSafe(string? ownerId)
+        {
+            return !string.IsNullOrWhiteSpace(ownerId) && !ownerId.Contains('/', StringComparison.Ordinal);
+        }
+    }
+}

src/AgentCore.Application/Configuration/Compilation/AgentToolCompiler.cs

@@ -101,7 +101,7 @@ private static void Add(
                 if (context.ChatClients.ResolveHostedTool(tool, model) is not { } resolved)
                 {
                     ILogger logger = context.Loggers?.CreateLogger(typeof(AgentToolCompiler)) ?? NullLogger.Instance;
-                    
+
                     string modelDescription = model is { Ref.Length: > 0 } ? $"the model '{model.Ref}'" : "this agent's default model";
 
                     Log.HostedToolDropped(logger, agentId, toolId, tool.GetType().Name, modelDescription);

src/AgentCore.Application/Configuration/Compilation/PolicyRow.cs

@@ -38,7 +38,7 @@ internal override EntryBuild BuildEntry(
                 StageConfiguration stage = policy.Stages[index];
                 string stagePointer = ConfigurationError.AppendPointer(
                     ConfigurationError.AppendPointer(policyPointer, "stages"), index);
-                    
+
                 if (stage.Agent is not { } agentId)
                 {
                     stages[stage.Id] = NoAgentId;

src/AgentCore.Application/Conversation/Conversations.cs

@@ -45,7 +45,7 @@ public Conversations(IConversationStore conversations, IBlobStore? blobs)
 
             IReadOnlyList<ConversationMessage> messages = await Store.ReadWindowAsync(conversationId, window, cancellationToken).ConfigureAwait(false);
 
-            IReadOnlyList<FileLink> files = await LinkFilesAsync(conversationId, messages.Select(message => message.Content), cancellationToken).ConfigureAwait(false);
+            IReadOnlyList<BlobRef> files = KeptFiles(conversationId, messages.Select(message => message.Content));
 
             int turns = messages.Select(message => message.TurnIndex).Distinct().Count();
 
@@ -55,15 +55,11 @@ public Conversations(IConversationStore conversations, IBlobStore? blobs)
             };
         }
 
-        /// <summary>Links every published file the messages carry and the store kept, each name once, in first-seen order.</summary>
+        /// <summary>Lists every published file the messages carry and the store kept, each name once, in first-seen order.</summary>
         /// <param name="conversationId">The conversation that owns the files.</param>
         /// <param name="messages">The messages to read the references off: the stored transcript, or one turn's updates.</param>
-        /// <param name="cancellationToken">Cancels the signing.</param>
-        /// <returns>One link per kept file.</returns>
-        public async Task<IReadOnlyList<FileLink>> LinkFilesAsync(
-            string conversationId,
-            IEnumerable<ChatMessage> messages,
-            CancellationToken cancellationToken = default)
+        /// <returns>The facts of each kept file. The last mention of a name wins its place's facts.</returns>
+        internal IReadOnlyList<BlobRef> KeptFiles(string conversationId, IEnumerable<ChatMessage> messages)
         {
             ArgumentException.ThrowIfNullOrWhiteSpace(conversationId);
             ArgumentNullException.ThrowIfNull(messages);
@@ -95,15 +91,22 @@ public async Task<IReadOnlyList<FileLink>> LinkFilesAsync(
                 }
             }
 
-            List<FileLink> links = [];
+            return kept;
+        }
 
-            foreach (BlobRef blob in kept)
+        /// <inheritdoc />
+        public async ValueTask<Uri?> LinkFileAsync(string conversationId, string name, CancellationToken cancellationToken = default)
+        {
+            if (_blobs is null || !BlobOwner.IsSafe(conversationId) || !BlobName.IsSafe(name))
             {
-                Uri? url = await _blobs.LinkAsync(blob, BlobLink.Lifetime, cancellationToken).ConfigureAwait(false);
-                links.Add(new FileLink(blob, url));
+                return null;
             }
 
-            return links;
+            BlobRef? blob = await _blobs.StatAsync(conversationId, name, cancellationToken).ConfigureAwait(false);
+
+            return blob is null
+                ? null
+                : await _blobs.LinkAsync(blob, BlobLink.Lifetime, cancellationToken).ConfigureAwait(false);
         }
 
         /// <inheritdoc />

src/AgentCore.Application/Conversation/StoredConversation.cs

@@ -1,4 +1,5 @@
 using AgentCore.Application.Blobs;
+using AgentCore.Application.Ports;
 using AgentCore.Application.Transcript;
 
 namespace AgentCore.Application.Conversation
@@ -7,13 +8,13 @@ namespace AgentCore.Application.Conversation
     /// <param name="Conversation">The row.</param>
     /// <param name="Messages">The stored messages, oldest first: every one, or one window's worth.</param>
     /// <param name="Files">
-    /// One link per file the messages name and the blob store kept, each name once, in first-seen order.
-    /// The links expire; read them out at once rather than keeping this record around.
+    /// The facts of each file the messages name and the blob store kept, each name once, in first-seen order.
+    /// A link to the bytes comes from <see cref="IConversations.LinkFileAsync"/> when the person asks for one.
     /// </param>
     public sealed record StoredConversation(
         ConversationRecord Conversation,
         IReadOnlyList<ConversationMessage> Messages,
-        IReadOnlyList<FileLink> Files)
+        IReadOnlyList<BlobRef> Files)
     {
         /// <summary>
         /// Gets the turn to read the next older window before, or <see langword="null"/> when