fix(reader): keep reader mode snapshot stable

README.md

@@ -39,7 +39,7 @@ Architect solves this with a grid view that keeps all your agents visible, with
 - **Selection-to-agent context** — release after selecting terminal text to reveal a narrow robot button anchored just outside the selection; the button follows the selection while scrolling; choose Claude, Codex, or Gemini in a centered modal with highlighted dropdown navigation, review the fully wrapped context in a scrollable field, enter wrapped multiline instructions, cancel if needed, or launch a new agent in the selected terminal's working directory with the selection submitted as its initial prompt without embedding large contexts in the shell command line
 - **Story viewer** — run `architect story <filename>` to open a scrollable overlay that renders PR story files with prose text and diff-colored code blocks
 - **MCP session spawning** — run `architect-mcp` from an MCP client to ask the running Architect app to create a terminal session in a requested working directory
-- **Reader mode** (⌘R) — open a centered markdown reader for the selected terminal's history (works in full view and grid) with live updates, bottom pinning, incremental search (⌘F, Enter/Shift+Enter), markdown tables with inline cell styling (bold/italic/code/links/strikethrough), task checkboxes (emoji), clickable links, shared draggable scrollbar, and left-to-right gradient separators before command prompts (OSC 133 + fallback heuristics)
+- **Reader mode** (⌘R) — open a centered markdown snapshot of the selected terminal's history (works in full view and grid); close and reopen it to capture newer output. Includes bottom pinning, incremental search (⌘F, Enter/Shift+Enter), markdown tables with inline cell styling (bold/italic/code/links/strikethrough), task checkboxes (emoji), clickable links, shared draggable scrollbar, and left-to-right gradient separators before command prompts (OSC 133 + fallback heuristics)
 
 ### Terminal Essentials
 - Smooth animated transitions for grid expansion, contraction, and reflow (cells and borders move/resize together)

docs/ARCHITECTURE.md

@@ -263,7 +263,7 @@ ui/components/markdown_parser.DisplayBlock[]
 ui/components/markdown_renderer.RenderLine[]
     | render as SDL text runs in centered reader column
     v
-Reader overlay (live updates + search)
+Reader overlay (open-time snapshot + search)
 ```
 
 ### Story Content Path
@@ -510,7 +510,7 @@ Rotate: rename active file to architect-<UTC timestamp>.log and continue in new
 | `ui/components/markdown_parser.zig` | Shared markdown parser for reader mode and story overlays. Parses headings, paragraphs, lists (including task checkboxes), blockquotes, markdown tables, fenced code, horizontal rules, inline styles (bold/italic/code/strikethrough/link), and prompt separator blocks. In story mode (`parseStory()`), additionally handles `story-diff` fenced blocks, code block metadata JSON, anchor extraction (`**[N]**` in prose, `<!--ref:N-->` in code), and per-line paragraph emission. | `parse()`, `parseStory()`, `freeBlocks()`, `DisplayBlock`, `StyledSpan`, `CodeBlockMeta`, `CodeLineKind`, `ParseOptions` | std |
 | `ui/components/markdown_renderer.zig` | Line layout engine that wraps parsed markdown blocks into renderable lines and style runs, including prompt-separator and story-specific line kinds (diff headers, diff lines, code lines with anchor/kind metadata) | `buildLines()`, `freeLines()`, `RenderLine`, `RenderRun` | `ui/components/markdown_parser` |
 | `ui/components/search_utils.zig` | Shared search utilities for overlays: case-insensitive substring find, match rebuilding, search bar rendering, and text texture creation | `SearchMatch`, `TextTex`, `findCaseInsensitive()`, `rebuildMatches()`, `renderSearchBar()`, `makeTextTexture()` | `gfx/primitives`, `font_cache`, `dpi`, `geom`, `c` |
-| `ui/components/reader_overlay.zig` | Fullscreen reader overlay for the selected terminal history (full view or grid selection) with live markdown updates, centered reading-width layout, bottom pinning, jump-to-bottom, incremental search, clickable links, shared scrollbar interactions, styled inline markdown in table cells, and left-to-right gradient prompt separators | `ReaderOverlayComponent`, `toggle()` | `ui/components/fullscreen_overlay`, `ui/components/scrollbar`, `ui/components/search_utils`, `app/terminal_history`, `ui/components/markdown_parser`, `ui/components/markdown_renderer`, `os/open`, `font_cache`, `geom`, `c` |
+| `ui/components/reader_overlay.zig` | Fullscreen reader overlay for an open-time snapshot of the selected terminal history (full view or grid selection) with centered reading-width layout, bottom pinning, jump-to-bottom, incremental search, clickable links, shared scrollbar interactions, styled inline markdown in table cells, and left-to-right gradient prompt separators | `ReaderOverlayComponent`, `toggle()` | `ui/components/fullscreen_overlay`, `ui/components/scrollbar`, `ui/components/search_utils`, `app/terminal_history`, `ui/components/markdown_parser`, `ui/components/markdown_renderer`, `os/open`, `font_cache`, `geom`, `c` |
 | `ui/components/modal_frame.zig` | Shared chrome for centered modal dialogs: full-window darkening scrim + rounded filled/bordered panel, and the Escape/⌘W dismiss-key check. Used by `confirm_dialog.zig` and `selection_agent_overlay.zig` so their scrim/panel rendering and dismissal keys can't drift independently | `renderScrimAndPanel()`, `isDismissKey()` | `gfx/primitives`, `geom`, `c` |
 | `ui/components/dropdown_menu.zig` | Reusable vertical list menu: owns open/hover/keyboard-nav state and the committed `selected` index, renders its own cached item-label textures, and reports a `.selected`/`.closed` event on click or Enter/Escape so the owning component reacts (persist the pick, or act on it immediately) instead of tracking hit-testing and highlight rendering itself. Used by `selection_agent_overlay.zig`'s agent selector and `diff_overlay.zig`'s "Send to agent" menu | `DropdownMenu`, `openMenu()`, `close()`, `handleKey()`, `handleClick()`, `handleMotion()`, `itemAt()`, `itemRect()`, `render()` | `gfx/primitives`, `font_cache`, `ui/text_render`, `geom`, `c` |
 | `ui/components/selection_agent_overlay.zig` | Selection action form with highlighted agent selector, multiline prompt field, fully wrapped and scrollable selected-context preview, viewport-bounded context textures, cached UI text, and launch action containing the selected terminal context | `SelectionAgentOverlayComponent`, `open()`, `formatAgentPrompt()` | `ui/text_edit`, `ui/text_render`, `ui/first_frame_guard`, `ui/components/modal_frame`, `ui/components/dropdown_menu`, `ui/components/scrollbar`, `gfx/primitives`, `font_cache`, `geom`, `c` |

src/main.zig

@@ -81,6 +81,7 @@ test {
     _ = @import("ui/components/pr_dropdown_model.zig");
     _ = @import("ui/components/pr_dropdown_repo.zig");
     _ = @import("ui/components/pr_dropdown_view.zig");
+    _ = @import("ui/components/reader_overlay.zig");
     _ = @import("ui/components/scrollbar.zig");
     _ = @import("ui/components/search_utils.zig");
     _ = @import("ui/components/selection_agent_overlay.zig");

src/ui/components/reader_overlay.zig

@@ -65,7 +65,6 @@ pub const ReaderOverlayComponent = struct {
     scrollbar_state: scrollbar.State = .{},
 
     session_index: usize = 0,
-    last_render_epoch: u64 = 0,
     wrap_cols: usize = 90,
     layout_char_w_px: c_int = 0,
     pinned_to_bottom: bool = true,
@@ -131,7 +130,7 @@ pub const ReaderOverlayComponent = struct {
         self.layout_char_w_px = 0;
         self.wrap_cols = self.computeWrapCols(host);
         self.overlay.show(now_ms);
-        self.refreshFromSession(host, true);
+        self.loadSnapshotFromSession(host, true);
         return .opened;
     }
 
@@ -169,15 +168,14 @@ pub const ReaderOverlayComponent = struct {
         markdown_renderer.freeLines(self.allocator, &self.lines);
         self.blocks = .empty;
         self.lines = .empty;
-        self.last_render_epoch = 0;
     }
 
     fn clearLinkHits(self: *ReaderOverlayComponent) void {
         self.link_hits.clearRetainingCapacity();
         self.hovered_link = null;
     }
 
-    fn refreshFromSession(self: *ReaderOverlayComponent, host: *const types.UiHost, force_bottom: bool) void {
+    fn loadSnapshotFromSession(self: *ReaderOverlayComponent, host: *const types.UiHost, force_bottom: bool) void {
         if (self.session_index >= self.sessions.len) return;
 
         const session = self.sessions[self.session_index];
@@ -197,7 +195,6 @@ pub const ReaderOverlayComponent = struct {
         };
 
         self.rebuildLines(host, force_bottom);
-        self.last_render_epoch = session.render_epoch;
     }
 
     fn rebuildLines(self: *ReaderOverlayComponent, host: *const types.UiHost, force_bottom: bool) void {
@@ -875,14 +872,9 @@ pub const ReaderOverlayComponent = struct {
             self.rebuildLines(host, false);
         }
 
-        if (self.session_index < self.sessions.len) {
-            const session = self.sessions[self.session_index];
-            if (session.render_epoch != self.last_render_epoch) {
-                self.refreshFromSession(host, false);
-            } else {
-                _ = self.syncScrollMetrics(host);
-            }
-        }
+        // Reader content is an open-time snapshot. Terminal output continues
+        // independently and is captured the next time the overlay opens.
+        _ = self.syncScrollMetrics(host);
 
         if (self.pinned_to_bottom) {
             self.overlay.scroll_offset = self.overlay.max_scroll;
@@ -1695,3 +1687,51 @@ pub const ReaderOverlayComponent = struct {
         .wantsFrame = wantsFrameFn,
     };
 };
+
+test "reader content stays a snapshot while the terminal updates" {
+    const allocator = std.testing.allocator;
+
+    var session: SessionState = undefined;
+    session.render_epoch = 2;
+    session.terminal = null;
+    var sessions = [_]*SessionState{&session};
+
+    var component = ReaderOverlayComponent{
+        .allocator = allocator,
+        .opener = undefined,
+        .sessions = &sessions,
+        .overlay = .{
+            .visible = true,
+            .animation_state = .open,
+        },
+        .session_index = 0,
+        .raw_text = try allocator.dupe(u8, "captured before live output"),
+    };
+    defer component.clearContent();
+
+    var host = types.UiHost{
+        .now_ms = 1_000,
+        .window_w = 1_200,
+        .window_h = 800,
+        .window_focused = true,
+        .ui_scale = 1.0,
+        .grid_cols = 1,
+        .grid_rows = 1,
+        .cell_w = 10,
+        .cell_h = 20,
+        .term_cols = 120,
+        .term_rows = 40,
+        .view_mode = .Full,
+        .focused_session = 0,
+        .focused_cwd = null,
+        .focused_has_foreground_process = true,
+        .sessions = &[_]types.SessionUiInfo{},
+        .theme = undefined,
+    };
+    var actions = types.UiActionQueue.init(allocator);
+    defer actions.deinit();
+
+    ReaderOverlayComponent.updateFn(&component, &host, &actions);
+
+    try std.testing.expectEqualStrings("captured before live output", component.raw_text.?);
+}