Web search for pi through an existing Chrome over CDP

Attaches to a browser that is already running — never launches one —
using the same endpoint configuration as pi-browser-harness, so a single
/browser-target choice governs both packages.

One tool, castle_cdp_search, deliberately not named web_search so it
coexists with pi-web-access rather than shadowing it.

Notes from validating against castle's Chrome:

- tbs=qdr:*, the parameter Google's own Tools menu writes, renders an
  empty page on this profile; the older as_qdr=* works. Any date filter
  combined with udm=14 is also empty, so recency drops udm.
- Target.createTarget must not be raced against the abort signal:
  raceAbort abandons the promise but cannot cancel the command, and the
  command's side effect is a tab nothing is left holding.
- A search cancelled while queued has to be removed from the semaphore
  queue, or the slot handed to it later is never counted back.
- A decaying rate-limit block stops serving /sorry/ and returns an empty
  results page instead, indistinguishable from a genuine zero-hit search.

1 files changed, 46 insertions, 0 deletions

diff --git a/src/format.ts b/src/format.ts
new file mode 100644
index 0000000..d3872a1
--- /dev/null
+++ b/src/format.ts
@@ -0,0 +1,46 @@
+/**
+ * Turning results into the text the model reads.
+ *
+ * Twenty results with 600-character snippets is roughly 15KB, comfortably under
+ * pi's 50KB / 2000-line budget — but the truncation is applied anyway rather
+ * than argued about, because a pathological page could blow past it and an
+ * overflowing tool result costs the whole session, not just this call.
+ */
+
+import type { SearchResult } from "./extract.ts";
+
+export type FormatInput = {
+  query: string;
+  searchUrl: string;
+  finalUrl: string;
+  endpoint: string;
+  results: SearchResult[];
+};
+
+export const formatResults = (input: FormatInput): string => {
+  const lines: string[] = [
+    `Search results for "${input.query}" (${input.results.length} hits, via Chrome at ${input.endpoint})`,
+    `Query URL: ${input.searchUrl}`,
+  ];
+  if (input.finalUrl !== input.searchUrl) lines.push(`Landed on: ${input.finalUrl}`);
+  lines.push("");
+
+  input.results.forEach((result, index) => {
+    lines.push(`${index + 1}. ${result.title}`);
+    lines.push(`   ${result.url}`);
+    if (result.snippet) lines.push(`   ${result.snippet}`);
+    lines.push("");
+  });
+
+  return lines.join("\n").trimEnd();
+};
+
+/**
+ * The note appended when pi's truncation utilities cut the output. Says what was
+ * lost and what to do about it — a bare "[truncated]" tells the model nothing it
+ * can act on, and there is no temp file to point at because the full text only
+ * ever existed in memory.
+ */
+export const truncationNote = (shown: number, total: number, bytesShown: string, bytesTotal: string): string =>
+  `\n\n[Output truncated: ${shown} of ${total} lines (${bytesShown} of ${bytesTotal}). ` +
+  `Re-run castle_cdp_search with a smaller numResults to see the rest.]`;