feat: add expand/collapse (Ctrl+O) rendering to web_search and read_page

Both tools dumped full output into the TUI. Add a shared renderExpandableText
helper (src/domains/render.ts) mirroring browser_execute_js: a compact preview
by default, full body on expand via keyHint("app.tools.expand"). Tools stash a
{summary, body, fullOutputPath} render payload in details; the full text still
goes to the LLM via ToolOk.text. Also surfaces engine + result count in the
web_search summary line (closes the S4 observability gap).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

1 files changed, 64 insertions, 0 deletions

diff --git a/src/domains/render.ts b/src/domains/render.ts
new file mode 100644
index 0000000..f6a6535
--- /dev/null
+++ b/src/domains/render.ts
@@ -0,0 +1,64 @@
+/**
+ * Shared TUI renderer for text-heavy tool output (browser_web_search,
+ * browser_read_page). Gives the native pi expand/collapse (Ctrl+O) behavior:
+ * a compact preview by default, the full body when expanded — mirroring the
+ * pattern in browser_execute_js (src/domains/js.ts:81-109).
+ *
+ * The full text always goes to the LLM via ToolOk.text; this only governs the
+ * human-facing TUI view.
+ */
+import { Markdown, Text } from "@mariozechner/pi-tui";
+import { getMarkdownTheme, keyHint } from "@mariozechner/pi-coding-agent";
+import type { Component } from "@mariozechner/pi-tui";
+import type { Theme } from "@mariozechner/pi-coding-agent";
+
+const COMPACT_PREVIEW_LINES = 6;
+
+/** Structured payload a text-heavy tool stores so renderResult can rebuild views. */
+export type ExpandableText = {
+  /** One-line summary shown above the body in both states (e.g. "5 results · google"). */
+  readonly summary: string;
+  /** The full rendered body (markdown/plain). */
+  readonly body: string;
+  /** Path to the on-disk full output when the LLM text was truncated, if any. */
+  readonly fullOutputPath?: string;
+};
+
+const isExpandableText = (value: unknown): value is ExpandableText => {
+  if (typeof value !== "object" || value === null) return false;
+  const v = value as Record<string, unknown>;
+  return typeof v["summary"] === "string" && typeof v["body"] === "string";
+};
+
+const extractRender = (details: unknown): unknown => {
+  if (typeof details !== "object" || details === null) return undefined;
+  return (details as Record<string, unknown>)["render"];
+};
+
+/**
+ * Build a renderResult over an ExpandableText stored in `details.render`.
+ * `label` names the tool for the error fallback (e.g. "web_search").
+ */
+export const renderExpandableText = (
+  label: string,
+  result: { readonly details?: unknown },
+  expanded: boolean,
+  theme: Theme,
+): Component => {
+  const render = extractRender(result.details);
+  if (!isExpandableText(render)) return new Text(theme.fg("error", `${label}: no details`), 0, 0);
+
+  if (!expanded) {
+    const lines = render.body.split("\n");
+    const preview = lines.slice(0, COMPACT_PREVIEW_LINES).join("\n");
+    const more = lines.length > COMPACT_PREVIEW_LINES ? `\n… ${lines.length - COMPACT_PREVIEW_LINES} more lines` : "";
+    const md = `**${render.summary}**\n\n${preview}${more}\n\n${keyHint("app.tools.expand", "to expand")}`;
+    return new Markdown(md, 0, 0, getMarkdownTheme());
+  }
+
+  const tail = render.fullOutputPath
+    ? `\n\nFull output at \`${render.fullOutputPath}\` · ${keyHint("app.tools.expand", "to collapse")}`
+    : `\n\n${keyHint("app.tools.expand", "to collapse")}`;
+  const md = `**${render.summary}**\n\n${render.body}${tail}`;
+  return new Markdown(md, 0, 0, getMarkdownTheme());
+};