diff --git a/MeetingAssistant.Tests/MeetingSummaryInstructionBuilderTests.cs b/MeetingAssistant.Tests/MeetingSummaryInstructionBuilderTests.cs
index 0131ad4..36b5732 100644
--- a/MeetingAssistant.Tests/MeetingSummaryInstructionBuilderTests.cs
+++ b/MeetingAssistant.Tests/MeetingSummaryInstructionBuilderTests.cs
@@ -24,6 +24,7 @@ public sealed class MeetingSummaryInstructionBuilderTests
         Assert.Contains("You are the Meeting Assistant summary agent.", instructions);
         Assert.Contains("include only the most relevant cropped screenshots", instructions);
         Assert.Contains("Do not include every cropped screenshot", instructions);
+        Assert.Contains("encode spaces in image-link targets as `%20`", instructions);
         Assert.Contains("Use add_attendee and remove_attendee", instructions);
         Assert.Contains("partial screenshot", instructions);
         Assert.Contains("override_speaker", instructions);
diff --git a/MeetingAssistant/Summary/MeetingSummaryInstructionBuilder.cs b/MeetingAssistant/Summary/MeetingSummaryInstructionBuilder.cs
index 8819f79..393ff84 100644
--- a/MeetingAssistant/Summary/MeetingSummaryInstructionBuilder.cs
+++ b/MeetingAssistant/Summary/MeetingSummaryInstructionBuilder.cs
@@ -22,7 +22,7 @@ public sealed class MeetingSummaryInstructionBuilder : IMeetingSummaryInstructio
         After writing the summary, update existing project files when the meeting produced durable project knowledge, decisions, next steps, or context.
         Use list_projects first to see which projects are bound to this meeting. Use search, list_past_project_meetings, read_past_project_meeting_summary, and read_projectfile before changing existing project files. search includes both project files and past meeting summaries for the requested current-meeting project scope.
         The summary note should contain concise sections for summary, decisions, open questions, and next steps.
-        If the assistant context contains cropped screenshot markdown links, include only the most relevant cropped screenshots in the summary by markdown-linking them near the related summary text. Do not include every cropped screenshot by default, and do not link uncropped screenshots unless no cropped version exists and the image is important.
+        If the assistant context contains cropped screenshot markdown links, include only the most relevant cropped screenshots in the summary by markdown-linking them near the related summary text. When embedding them, encode spaces in image-link targets as `%20`; never leave literal spaces in the link target. Do not include every cropped screenshot by default, and do not link uncropped screenshots unless no cropped version exists and the image is important.
         Keep the output grounded in the source material and explicitly say when a section has no known items.
         """;