[ochafik]

Summary

The pdf-server viewer saves the current page to localStorage (keyed by viewUUID) and is meant to restore it when a host re-renders the same tool call — reopening a conversation, refreshing the page. In practice annotations came back but the page didn't. Root cause: the restore guard

currentPage = savedPage && savedPage <= parsed.pageCount ? savedPage : parsed.initialPage;

compares against structuredContent.pageCount, a field display_pdf stopped sending in #329 when server-side PDF parsing was removed. savedPage <= undefined is always false, so the saved page has been read and discarded on every load since — dead code for ~9 months.

Changes

• Restore the saved page unconditionally (loadSavedPage() already validates >= 1) and clamp to totalPages once the document loads — the same clamp reloadPdf() already has; the bounds check simply can't happen before the document is parsed.
• Resolve viewUUID from _meta with a structuredContent fallback. The server sends it in both places, and some hosts drop _meta when replaying cached tool results — in that case the viewer previously had no storage key at all (so neither page nor, pre-Add get_current_pdf to the pdf-server example (app tool + interact action) #820-era keys aside, anything else keyed on it could restore). This also tracks the broader "dual-channel critical fields" hardening direction.
• Drop pageCount from the parsed-result type — it was never sent, and the lying type is what hid the bug.

Test

New e2e (tests/e2e/pdf-page-restore.spec.ts) that exercises the real restore path: the basic-host test UI doesn't replay tool results (#642), so the test plays the host — it captures the display_pdf CallToolResult from the result panel, navigates to another page via the view's own navigate tool (which persists it), then re-posts the captured result into the app iframe as a ui/notifications/tool-result notification and asserts the viewer comes back on the saved page, not initialPage. Two variants: with the original _meta, and with _meta stripped (covers the structuredContent fallback).

Validation

• tsc --noEmit (example tsconfig) — clean
• bun test examples/pdf-server src — 441 tests, 0 failures
• Both new e2e tests pass; the pre-existing pdf e2e suites pass apart from unrelated server-boot timing flakes on the (slow) validation machine — they are green on main's CI and this diff doesn't touch boot paths.

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