Merge pull request #1358 from helenkwok/web/embedding-bridge

feat(web): a host bridge for embedding pages, ?host=parent and data-host="page" (#1356)

Cargo.lock

@@ -1157,6 +1157,15 @@ dependencies = [
  "zip 9.1.1",
 ]
 
+[[package]]
+name = "craft-web-host"
+version = "0.1.0"
+source = "git+https://github.com/storytold/craft-libs?rev=2e2312ddaf21bc3d85cd3395d0955c7d239306f6#2e2312ddaf21bc3d85cd3395d0955c7d239306f6"
+dependencies = [
+ "wasm-bindgen",
+ "web-sys",
+]
+
 [[package]]
 name = "craft-window"
 version = "0.1.0"
@@ -2121,6 +2130,7 @@ name = "figcraft-web"
 version = "0.15.0"
 dependencies = [
  "base64 0.22.1",
+ "craft-web-host",
  "eframe",
  "egui",
  "figcraft-collab-net",

ROADMAP.md

@@ -2,7 +2,7 @@
 
 **Stage: alpha** · next: beta, ~26 points and ~162–292 h away (one Opus 5.5 agent; ~33–67 h wall-clock with 5 agents)
 
-> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-30 · **Change:** minor (a connector end moved with Cmd/Ctrl held goes on any part of an object, and stays there as the object moves or resizes; a tap on a plugin panel's button keeps what was typed in its fields; a Dash cap setting (none, round or square) on Dash and Custom strokes, drawn on both ends of every dash; library analytics list how many layers and files use each style and variable; the Controller menu names each button as PlayStation and Switch controllers do; widgets draw lines and SVG pictures (plugin API 6); a connector end dropped along a side of a shape attaches to that side (#1708); regression tests pin a rounded shape's one-sided stroke and SVG ids and font families without XML-forbidden characters (#1351, #1124); a damaged image is refused with a reason instead of showing as an empty box (#1474); an image copied in another app pastes again on the desktop, and in the browser for the first time (#492); SwiftUI and Compose code names a bound variable by its iOS or Android code syntax; the colour picker's Image tab shows a placeholder and Upload from computer, an asset preview, and a file dropped on it replaces the image, keeping the fill mode, crop and position (#1682); the Frame tool's Phone presets have the iPhone 17 family (#1691); Show in folder works in the Flatpak build and selects the file on Linux (#1701); a dashed line starts and ends with a half-length dash, on the canvas and in exports; the Pages, Layers and Assets search fields keep their text in the middle of the field (#1703); a board connector's path can be reshaped by dragging its path handles (#1710); boards have 16 more shapes (arrows, polygons, star, plus and flowchart symbols), in pickers that lay them out in a grid; library analytics count insertions and show insertions and detachments over the past 30 days, 90 days or year; a stroke's Custom style takes a dash pattern of any length as a comma-separated list (#1681); a control request can set its own timeout, up to 10 minutes (`timeoutMs`; `figcraft-cli mcp --attach PORT --timeout SECONDS`) (#1696); gap 6: a widget opens its plugin's panel (plugin API 5), whose callbacks redraw it; the keyboard's Menu key opens the context menu, as Shift+F10 does; an Open link action can open in place of the prototype, with "Open in new tab" off (gap 15); a collection of this file can be extended (Extend collection on its row, `variable.extendCollection`), its extension following its edits at once, and extended collections extend again in the file; the eyedropper with Cmd/Ctrl+Shift makes a colour style or variable of what it picks; a live session's welcome sends the document compressed to clients that read it, about seven times smaller (#1665); a control request that times out says truthfully whether it was dropped or is still running and will take effect, and only screenshots and input blame the window (#1673); a board keeps earlier votes' results, listed newest first in Results and deleted one at a time; the object a stamp will stick to is outlined while the stamp tool is over it or a stamp is dragged over it, and board objects take no drops (gap 24); a server can list the files shared from it now for everyone who reaches it, Home ▸ Online shows them and their links carry no secret (`team_files`, part of #742); team library analytics count detached instances per component and file (gap 10); skipping the Open link notice by command is saved with the preferences at once (gap 15); a selected connector's bar on a board sets its start and end points, solid or dashed, its weight and any colour (#1596); cells copied from a spreadsheet paste onto a board as a table; a long layer name stays on one line in the Export button and the Dev Mode header, ending with an ellipsis, and no longer covers the Design panel (#1650); with hundreds of layers selected, the Design panel and the selection overlays stop going over the whole selection on every frame, so dragging 648 layers averages about 1.1 ms of UI per frame (#1571); plugin panels show pictures: an `image` control, base64 within 256 KB and 4,096 px a side, named by its label (gap 6); `.fig` connector labels without a saved snapshot are kept, centred on their line (gap 1); a drag moving many layers re-runs only what sits around them, not each layer's bindings, sizing, text and instance checks, on every move (#1571); damaged font tracking table offsets are checked instead of wrapping on 32-bit targets, and font indexing makes its existing offset bounds explicit (#1125); Bosnian (`bs`) draft catalog; text style dedupe is O(spans) via a last-two cache and fingerprint buckets (#1102); pasted layers whose image the clipboard lacks are named and show a placeholder that reads as missing (#1646); paint-style colours on layers pasted from another design app keep their style instead of turning black (#1638); progress docs cleaned of what merges left twice: rows merged into one, repeated statusLine truncated
+> **Last reviewed:** 2026-10-10 · **Last updated:** 2026-10-30 · **Change:** minor (web host bridge: `?host=parent` or `data-host="page"` hands a page the app's files, documented in the hosting guide; a connector end moved with Cmd/Ctrl held goes on any part of an object, and stays there as the object moves or resizes; a tap on a plugin panel's button keeps what was typed in its fields; a Dash cap setting (none, round or square) on Dash and Custom strokes, drawn on both ends of every dash; library analytics list how many layers and files use each style and variable; the Controller menu names each button as PlayStation and Switch controllers do; widgets draw lines and SVG pictures (plugin API 6); a connector end dropped along a side of a shape attaches to that side (#1708); regression tests pin a rounded shape's one-sided stroke and SVG ids and font families without XML-forbidden characters (#1351, #1124); a damaged image is refused with a reason instead of showing as an empty box (#1474); an image copied in another app pastes again on the desktop, and in the browser for the first time (#492); SwiftUI and Compose code names a bound variable by its iOS or Android code syntax; the colour picker's Image tab shows a placeholder and Upload from computer, an asset preview, and a file dropped on it replaces the image, keeping the fill mode, crop and position (#1682); the Frame tool's Phone presets have the iPhone 17 family (#1691); Show in folder works in the Flatpak build and selects the file on Linux (#1701); a dashed line starts and ends with a half-length dash, on the canvas and in exports; the Pages, Layers and Assets search fields keep their text in the middle of the field (#1703); a board connector's path can be reshaped by dragging its path handles (#1710); boards have 16 more shapes (arrows, polygons, star, plus and flowchart symbols), in pickers that lay them out in a grid; library analytics count insertions and show insertions and detachments over the past 30 days, 90 days or year; a stroke's Custom style takes a dash pattern of any length as a comma-separated list (#1681); a control request can set its own timeout, up to 10 minutes (`timeoutMs`; `figcraft-cli mcp --attach PORT --timeout SECONDS`) (#1696); gap 6: a widget opens its plugin's panel (plugin API 5), whose callbacks redraw it; the keyboard's Menu key opens the context menu, as Shift+F10 does; an Open link action can open in place of the prototype, with "Open in new tab" off (gap 15); a collection of this file can be extended (Extend collection on its row, `variable.extendCollection`), its extension following its edits at once, and extended collections extend again in the file; the eyedropper with Cmd/Ctrl+Shift makes a colour style or variable of what it picks; a live session's welcome sends the document compressed to clients that read it, about seven times smaller (#1665); a control request that times out says truthfully whether it was dropped or is still running and will take effect, and only screenshots and input blame the window (#1673); a board keeps earlier votes' results, listed newest first in Results and deleted one at a time; the object a stamp will stick to is outlined while the stamp tool is over it or a stamp is dragged over it, and board objects take no drops (gap 24); a server can list the files shared from it now for everyone who reaches it, Home ▸ Online shows them and their links carry no secret (`team_files`, part of #742); team library analytics count detached instances per component and file (gap 10); skipping the Open link notice by command is saved with the preferences at once (gap 15); a selected connector's bar on a board sets its start and end points, solid or dashed, its weight and any colour (#1596); cells copied from a spreadsheet paste onto a board as a table; a long layer name stays on one line in the Export button and the Dev Mode header, ending with an ellipsis, and no longer covers the Design panel (#1650); with hundreds of layers selected, the Design panel and the selection overlays stop going over the whole selection on every frame, so dragging 648 layers averages about 1.1 ms of UI per frame (#1571); plugin panels show pictures: an `image` control, base64 within 256 KB and 4,096 px a side, named by its label (gap 6); `.fig` connector labels without a saved snapshot are kept, centred on their line (gap 1); a drag moving many layers re-runs only what sits around them, not each layer's bindings, sizing, text and instance checks, on every move (#1571); damaged font tracking table offsets are checked instead of wrapping on 32-bit targets, and font indexing makes its existing offset bounds explicit (#1125); Bosnian (`bs`) draft catalog; text style dedupe is O(spans) via a last-two cache and fingerprint buckets (#1102); pasted layers whose image the clipboard lacks are named and show a placeholder that reads as missing (#1646); paint-style colours on layers pasted from another design app keep their style insLine truncated
 
 FigCraft is a clean-room, open-source, pure-Rust reimplementation of the Figma design workflow,
 native on macOS, Windows, Linux and FreeBSD and in the browser, fully drivable by agents through
@@ -143,6 +143,7 @@ Ranked; detail and milestones in [`docs/roadmap.md`](docs/roadmap.md).
 - **2026-10-27** · Batch continue-on-error (M0.9, #1386): `command.batch` and MCP `batch` accept `onError: "continue"`, roll back failed steps individually and return one outcome per step. References to failed steps fail with both step numbers; successful edits stay one undo step, and the default abort mode is unchanged. Engine and MCP regression tests. Numbers unchanged.
 - **2026-10-26** · Non-ASCII layer names transliterate in code export (M6, #1235): `class_name` runs the name through `deunicode` before its ASCII filter, so 로그인 화면 → `rogeuin-hwamyeon`, кнопка → `knopka`, über → `uber` in the HTML/CSS/React/Leptos class names, component roots and `data-*` variant attributes (SwiftUI/Compose type names unchanged); a name left with nothing (symbols only) takes the node's kind (`.text`, `.frame`) instead of `layer-`, and the 40-character cut lands on a word boundary. New dependency: deunicode (pure Rust tables, zero deps, BSD-3-Clause, the `slug` crate's base). `html_codegen_tests`. Numbers unchanged.
 - **2026-10-25** · M6, #1143: offline Penpot 2.x open/import/export through the editor, CLI and MCP using the existing document model. Unsupported layout settings retain saved positions and bounded source metadata with warnings; font binaries and toggle-overlay are reported, and provider fonts are never downloaded. Shared ZIP/JSON/token budgets guard untrusted input. Figma parity numbers unchanged.
+- **2026-10-26** · Web host bridge: `?host=parent` (a same-origin page embedding FigCraft in an iframe) or `data-host="page"` on the canvas (the page's own document, over non-bubbling `CustomEvent`s) opens the host's file like File ▸ Open (over the browser open limit of 512 MB refused) and takes every file the app would otherwise download (`figcraft:save` with the `saveAs` rule), plus `figcraft:dirty`, `figcraft:ready` and `figcraft:failed`; `?author=` names the user for comments and board notes; host mode starts with no document. Unit tests cover the opt-in rule (only the exact `page` value), the `saveAs` rule and the open-name fallback. Numbers unchanged.
 - **2026-10-25** · egui 0.37 capture lifecycle: screenshots with hidden or unknown visibility queue, request a hidden paint, and expire after 60 seconds if no capture arrives (headless-tested contract). Logic-only edits, saves and inspection continue while hidden. Native visible GUI and forced hidden-window paint, browser and Wayland behavior remain unqualified; parity percentages are unchanged.
 - **2026-10-24** · Open, Save and the folder dialogs start in the folder of the last file or folder picked in the run (#1290): the Linux portal does not remember it between dialogs as the macOS and Windows panels do. A folder deleted since falls back to the system's choice. No numbers change.
 - **2026-10-24** · Boards (M12): board pages get a dot grid under their layers (drawn by the canvas render after the page colour, thinned out when zoomed out); a selected connector shows its ends as handles, and dragging one onto another object re-attaches it there, onto empty canvas leaves it free (`board.reattach`, one undo step, also over MCP); connectors can be curved, and elbows go around the objects they join when the short way would cross them. Checked in the app, through MCP and in the web build ([boards-parity](docs/boards-parity.md)).
@@ -492,6 +493,7 @@ Ranked; detail and milestones in [`docs/roadmap.md`](docs/roadmap.md).
 | 2026-10-27 | minor | Placed images keep their own size (M7, #1360): dropping, Place image, paste and `image.place` put an image at its pixel size and fit only a side past 4096 px (they fitted it into 1000 px); a PNG whose `pHYs` records a whole 2x–4x multiple of 72 dpi (macOS screenshots record 144 dpi) is placed at its point size, so an 800 × 600 px capture comes in at 400 × 300; other densities, such as 300 dpi scans, keep their pixel size; the image data stays at full resolution and an explicit width or height still wins. On macOS, paste reads the clipboard's PNG as is (its density and colour profile kept) and falls back to the decoded image. Numbers unchanged |
 | 2026-10-26 | minor | Non-ASCII layer names transliterate in code export (M6, #1235): `class_name` transliterates through the new `deunicode` dependency (pure Rust tables, zero deps, BSD-3-Clause), so Korean, Cyrillic, Latin-diacritic and CJK names become readable ASCII classes (`rogeuin-hwamyeon`, `knopka`, `uber`, `an-niu`) in HTML/CSS/React/Leptos output, component roots and `data-*` variant attributes; symbols-only names take the node's kind (`.text`) instead of `layer-`, and the 40-character cut lands on a word boundary. `html_codegen_tests` updated and extended. Numbers unchanged |
 | 2026-10-25 | minor | M6, #1143: offline Penpot 2.x open/import/export through the editor, CLI and MCP using the existing document model. Unsupported layout settings retain saved positions and bounded source metadata with warnings; font binaries and toggle-overlay are reported, and provider fonts are never downloaded. Shared ZIP/JSON/token budgets guard untrusted input. Figma parity numbers unchanged. |
+| 2026-10-26 | minor | Web host bridge: `?host=parent` (a same-origin page embedding FigCraft in an iframe) or `data-host="page"` on the canvas (the page's own document, over non-bubbling `CustomEvent`s) opens the host's file like File ▸ Open and takes every file the app would otherwise download, with `figcraft:ready`, `figcraft:open`, `figcraft:save` (a `saveAs` rule), `figcraft:dirty` and `figcraft:failed`; `?author=` names the user for comments and board notes; documented in the hosting guide. Numbers unchanged |
 | 2026-10-25 | minor | egui 0.37 capture lifecycle: screenshots with hidden or unknown visibility queue, request a hidden paint, and expire after 60 seconds if no capture arrives (headless-tested contract). Logic-only edits, saves and inspection continue while hidden. Native visible GUI and forced hidden-window paint, browser and Wayland behavior remain unqualified; parity percentages are unchanged. |
 | 2026-10-24 | minor | Server memory (#1134): when the last person leaves a file nobody edited, figcraft-server keeps the client ids it issued in the log instead of rewriting the snapshot (compaction still follows `compact_after`/`compact_mb` and edits), and a snapshot is encoded straight into its file buffer, without a second copy of the body; the file format is unchanged. Numbers unchanged |
 | 2026-10-24 | minor | Boards (M12): a dot grid on board pages under the layers, connector ends dragged onto other objects or empty canvas (`board.reattach`), curved connectors, elbows that go around what they join. Boards row ~35% → ~37%, ~20% → ~21%, 30–60 h → 28–56 h; headline numbers unchanged (boards are outside the weighted sum) |

apps/figcraft-web/Cargo.toml

@@ -19,6 +19,8 @@ figcraft-format = { workspace = true }
 figcraft-ui-egui = { workspace = true }
 figcraft-collab-net = { workspace = true }
 figcraft-text = { workspace = true }
+# The host messages (storytold/craft-libs): one contract and one bridge for the web builds.
+craft-web-host = { git = "https://github.com/storytold/craft-libs", rev = "2e2312ddaf21bc3d85cd3395d0955c7d239306f6", version = "0.1.0" }
 base64 = { workspace = true }
 egui = { workspace = true }
 log = { workspace = true }
@@ -30,4 +32,4 @@ eframe = { workspace = true, features = ["default_fonts", "wgpu", "accesskit"] }
 wasm-bindgen = "0.2"
 js-sys = "0.3"
 wasm-bindgen-futures = "0.4"
-web-sys = { version = "0.3", features = ["Window", "Document", "Element", "HtmlCanvasElement", "HtmlElement", "HtmlAnchorElement", "Node", "Blob", "BlobPropertyBag", "ClipboardEvent", "DataTransfer", "File", "FileList", "HtmlInputElement", "EventTarget", "Url", "Location", "MediaQueryList", "Navigator", "Gamepad", "GamepadButton", "GamepadMappingType", "Storage"] }
+web-sys = { version = "0.3", features = ["Window", "Document", "Element", "HtmlCanvasElement", "HtmlElement", "HtmlAnchorElement", "Node", "Blob", "BlobPropertyBag", "ClipboardEvent", "DataTransfer", "File", "FileList", "HtmlInputElement", "EventTarget", "Url", "Location", "MediaQueryList", "Navigator", "Gamepad", "GamepadButton", "GamepadMappingType", "Storage", "Event", "MessageEvent", "UrlSearchParams", "CustomEvent", "CustomEventInit"] }

apps/figcraft-web/src/host.rs

@@ -0,0 +1,138 @@
+//! Host modes: a page that runs FigCraft (as an `<iframe>`, or in its own document) opens
+//! documents in it and stores what it saves instead of the browser downloading. The messages
+//! and the two transports are `craft-web-host`'s (storytold/craft-libs): the same contract as
+//! the other Craft apps' bridges. This module is FigCraft's part of it.
+//!
+//! - `?host=parent` (an `<iframe>`, such as a Nextcloud app) talks to the same-origin parent over
+//!   `postMessage`; `data-host="page"` on the canvas (the page's own document) uses DOM
+//!   `CustomEvent`s on the canvas instead. `?host=parent` wins when both are present.
+//! - `figcraft:ready` (to the host) once the app is running and listening; send a file now.
+//! - `figcraft:open` (from the host): `{ name, bytes }`. It opens exactly as a file picked with
+//!   File › Open or dropped on the window would (the app's own open queue, with its "Opening as
+//!   a new file" card). A payload over the browser's own open limit
+//!   ([`figcraft_ui_egui::browser_can_read`]'s 512 MB) is refused before its bytes are copied,
+//!   and anything malformed is ignored. FigCraft reads whole files, so it says `file: false` in
+//!   `ready` and a host sends `bytes`.
+//! - `figcraft:save` (to the host): `{ name, saveAs, bytes }` for every file the app hands its
+//!   download service; in host mode nothing reaches the browser's downloads. `saveAs` says whether
+//!   the file becomes the document's file ([`crate::hostmode::save_as`]):
+//!   - A Save of the file the host opened, under its own name: `false`.
+//!   - A document file (`.figcraft` or `.json`, the formats `file.save` and `file.saveAs` write)
+//!     under a name the host didn't open — Save As, or a Save of a document the host never sent
+//!     (an untitled one): `true`. It becomes the document's file; the next Save sends its name
+//!     with `false`. Names compare without case.
+//!   - Everything else is a copy or export that never becomes the document: `false` — rendered
+//!     images, SVG and PDF, `.fig` copies, and the variables exports (a `.variables.json`
+//!     sidecar's `.json` extension doesn't make it a document).
+//! - `figcraft:dirty` whenever unsaved changes appear or go away, `figcraft:failed` when the app
+//!   couldn't start.
+//!
+//! In host mode the app starts with no document (the home screen) and the host sends the file to
+//! edit; `?author=` names the user for comments and board notes.
+
+use std::cell::RefCell;
+use std::rc::Rc;
+
+use craft_web_host::web::{FileData, Host, Message};
+use figcraft_ui_egui::FigApp;
+
+/// The app id in the host messages (`figcraft:ready`).
+const APP: &str = "figcraft";
+
+/// The longest user name taken from `?author=`.
+const MAX_AUTHOR_CHARS: usize = 200;
+
+/// Files the host sent, on their way to the app's own open queue ([`figcraft_ui_egui::pending_open`]):
+/// `(name, bytes)`.
+pub type OpenQueue = Rc<RefCell<Vec<(String, Vec<u8>)>>>;
+
+#[derive(Clone)]
+pub struct Bridge {
+    host: Rc<Host>,
+    /// The file the host opened, and after a `saveAs` hand-over the document's file: the name a
+    /// Save under (`saveAs: false`) is decided against.
+    host_file: Rc<RefCell<Option<String>>>,
+}
+
+impl Bridge {
+    /// The bridge for this page, or `None` when FigCraft isn't hosted: no `?host=parent` and no
+    /// `data-host="page"` on the canvas, an unframed `?host=parent` page (it stays the normal app
+    /// with downloads), or a parent on another origin.
+    pub fn connect(canvas: &web_sys::HtmlCanvasElement) -> Option<Self> {
+        Some(Self { host: Rc::new(Host::connect(APP, canvas)?), host_file: Rc::default() })
+    }
+
+    /// Hear the files the host sends, and queue each one on `opens` for the app's own open path
+    /// (the shell drains it into [`figcraft_ui_egui::pending_open`] every frame, so a host file
+    /// opens like a dropped one).
+    pub fn listen(&self, opens: OpenQueue, ctx: egui::Context) {
+        let host_file = self.host_file.clone();
+        self.host.listen(move |message| {
+            if let Message::Open { name, data } = message {
+                deliver_open(&opens, &ctx, &host_file, &name, &data);
+            }
+        });
+    }
+
+    /// `?author=`: the host's name for the user signs comments and board notes.
+    pub fn set_author(app: &mut FigApp, author: &str) {
+        let author: String = author.trim().chars().take(MAX_AUTHOR_CHARS).collect();
+        if !author.is_empty() {
+            app.session.prefs.user_name = author;
+        }
+    }
+
+    pub fn post_ready(&self) {
+        let _ = self.host.post_ready(env!("CARGO_PKG_VERSION"), false);
+    }
+
+    /// The app couldn't start (no WebGPU or WebGL2, for example): let the host say so.
+    pub fn post_failed(&self, error: &str) {
+        let _ = self.host.post_failed(error, None);
+    }
+
+    /// Hand a file the app would otherwise download to the host; `false` when nothing was
+    /// delivered. The `saveAs` rule is this module's documentation's.
+    pub fn post_save(&self, path: &str, bytes: &[u8]) -> bool {
+        let name = file_name(path);
+        let host_file = self.host_file.borrow().clone();
+        let save_as = crate::hostmode::save_as(&name, host_file.as_deref());
+        let sent = self.host.post_save(&name, bytes, None, save_as).is_ok();
+        // After a Save As hand-over the host has the new file: the next Save of it sends its name
+        // with `saveAs: false`. A failed send changes nothing, so a retry is still a Save As.
+        if sent && save_as {
+            *self.host_file.borrow_mut() = Some(name);
+        }
+        sent
+    }
+
+    /// Report unsaved changes when they appear or go away, not every frame (the crate does not
+    /// repeat a state it already reported).
+    pub fn set_dirty(&self, dirty: bool) {
+        self.host.post_dirty(dirty);
+    }
+}
+
+/// The file an open message carries, queued for the app's own open path, or nothing when the
+/// payload isn't one (a `File` the app doesn't read, or over the open limit).
+fn deliver_open(opens: &OpenQueue, ctx: &egui::Context, host_file: &RefCell<Option<String>>, name: &str, data: &FileData) {
+    let name = crate::hostmode::open_name(name);
+    let FileData::Bytes(array) = data else {
+        log::warn!("host file {name} came as a File; FigCraft reads bytes only; not opened");
+        return;
+    };
+    if figcraft_ui_egui::browser_can_read(&name, data.size()).is_err() {
+        log::warn!("host file {name} is too large to open in the browser; not opened");
+        return;
+    }
+    // The document's file is now the one the host sent: a Save of it under this name is
+    // `saveAs: false`.
+    *host_file.borrow_mut() = Some(name.clone());
+    opens.borrow_mut().push((name, array.to_vec()));
+    ctx.request_repaint();
+}
+
+/// The last component of `path`, or the whole of it when there is none.
+fn file_name(path: &str) -> String {
+    std::path::Path::new(path).file_name().map(|n| n.to_string_lossy().to_string()).unwrap_or_else(|| path.to_string())
+}

apps/figcraft-web/src/hostmode.rs

@@ -0,0 +1,92 @@
+//! Pure host-mode rules, shared by the bridge ([`crate::host`]) and testable without a browser
+//! (like [`crate::query`]): the name the bridge fills in when an open request has none, and whether
+//! a handed-over file becomes the document's file. Which pages host the app is `craft-web-host`'s.
+
+/// The file name used when an open request carries no usable one.
+pub const DEFAULT_OPEN_NAME: &str = "Untitled.figcraft";
+
+/// The extensions of files that can be a document's own file: the formats `file.save` and
+/// `file.saveAs` write (`file.open` opens both as native documents). A `.fig` file is an export
+/// copy instead, and so is everything else the app hands over (rendered images, SVG, PDF,
+/// variables).
+const DOC_EXTS: &[&str] = &["figcraft", "json"];
+
+/// The suffix `variable.export`'s downloads carry: a `.json` that is a variables sidecar, not a
+/// document, so its extension alone can't tell the `saveAs` decision.
+const VARIABLES_SIDECAR: &str = ".variables.json";
+
+/// The name `craft-web-host` gives an open request that carries no usable one (it cleans a host's
+/// name and falls back to this).
+const NAMELESS: &str = "document";
+
+/// A usable file name for an open request: the cleaned name the crate hands over, or
+/// [`DEFAULT_OPEN_NAME`] when the host sent none.
+pub fn open_name(name: &str) -> String {
+    if name == NAMELESS { DEFAULT_OPEN_NAME.to_string() } else { name.to_string() }
+}
+
+/// Whether the file `name` becomes the document's own file when handed over (`saveAs: true`),
+/// given the file the host opened (`None`: the host never sent one). The rule:
+///
+/// - A document file (`.figcraft` or `.json`, [`DOC_EXTS`]'s formats) under a name the host didn't
+///   open — Save As, or a Save of a document the host never sent — is the document's new file:
+///   `true`. Names compare without case.
+/// - A Save of the host's own file under its name is not: `false`.
+/// - Everything else is a copy or export that never becomes the document — rendered images, SVG,
+///   PDF, `.fig` copies, variables — and the variables sidecar counts as one whatever its `.json`
+///   extension says: `false`.
+pub fn save_as(name: &str, host_file: Option<&str>) -> bool {
+    if name.to_ascii_lowercase().ends_with(VARIABLES_SIDECAR) {
+        return false;
+    }
+    let ext = std::path::Path::new(name).extension().and_then(std::ffi::OsStr::to_str);
+    if !ext.is_some_and(|e| DOC_EXTS.iter().any(|x| x.eq_ignore_ascii_case(e))) {
+        return false;
+    }
+    match host_file {
+        Some(host) => !host.eq_ignore_ascii_case(name),
+        None => true,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn open_names_fall_back_to_the_default_when_the_host_sent_none() {
+        assert_eq!(open_name("Poster.figcraft"), "Poster.figcraft");
+        assert_eq!(open_name("Poster 2.json"), "Poster 2.json");
+        assert_eq!(open_name("document"), DEFAULT_OPEN_NAME, "what the crate says for a missing or blank name");
+    }
+
+    #[test]
+    fn a_save_of_the_host_s_file_is_not_save_as() {
+        assert!(!save_as("Poster.figcraft", Some("Poster.figcraft")));
+        assert!(!save_as("poster.FIGCRAFT", Some("Poster.figcraft")), "names compare without case");
+        assert!(!save_as("design.json", Some("design.json")));
+    }
+
+    #[test]
+    fn a_new_document_file_is_save_as() {
+        assert!(save_as("Poster 2.figcraft", Some("Poster.figcraft")));
+        assert!(save_as("Poster.json", Some("Poster.figcraft")), "the other format a document's file takes");
+        assert!(save_as("Untitled.figcraft", None), "the host never sent a file");
+        assert!(save_as("Poster.figcraft", Some("design.json")), "the opened .json saved as .figcraft is a new file");
+    }
+
+    #[test]
+    fn copies_and_exports_never_become_the_document_s_file() {
+        for name in ["Poster.png", "Poster@2x.jpg", "Poster.svg", "Poster.pdf", "Poster.fig", "Poster.csv", "Poster.variables.css"] {
+            assert!(!save_as(name, Some("Poster.figcraft")), "{name} is a copy");
+            assert!(!save_as(name, None), "{name} is a copy even without a host file");
+        }
+    }
+
+    #[test]
+    fn the_variables_sidecar_is_a_copy_whatever_its_extension() {
+        assert!(!save_as("Poster.variables.json", Some("Poster.figcraft")));
+        assert!(!save_as("Poster.variables.json", None));
+        assert!(!save_as("design.variables.json", Some("design.variables.json")));
+    }
+}

apps/figcraft-web/src/main.rs

@@ -19,9 +19,17 @@
 //!   server…), but can't host a session. A page served over `https://` reaches only `wss://`
 //!   servers and the same computer (browsers block `ws://` from secure pages); serve it over
 //!   `http://` on a trusted network to reach plain `ws://` hosts on other machines.
+//! - host mode: `?host=parent` (a same-origin page embedding FigCraft in an `<iframe>`) or
+//!   `data-host="page"` on the canvas (the page's own document) hands the page the app's files
+//!   instead of downloading them and reports unsaved changes (`host`);
+//! - live sessions: it joins sessions a desktop app hosts (File ▸ Join live session…) but can't
+//!   host one. A page served over `https://` can only reach sessions on the same computer
 //!
 //! URL query flags: `?webgl` forces the WebGL2 backend instead of WebGPU; `?control` installs
-//! `window.figcraft`, the page's control channel (`api.rs`), which is off without it.
+//! `window.figcraft`, the page's control channel (`api.rs`), which is off without it; `?host=parent`
+//! (inside an `<iframe>`) talks to a same-origin parent page instead: it sends the document to open
+//! and stores what FigCraft saves. `&author=` names the user for comments and board notes in either
+//! host mode.
 //!
 //! URL fragment: `#join=<invite link or join code>` joins that live session once the page has
 //! loaded, so a bookmark opens a shared file. `join` takes the rest of the fragment: put it last.
@@ -30,6 +38,10 @@
 
 #[cfg(target_arch = "wasm32")]
 mod api;
+#[cfg(target_arch = "wasm32")]
+mod host;
+#[cfg(any(target_arch = "wasm32", test))]
+mod hostmode;
 #[cfg(any(target_arch = "wasm32", test))]
 mod kept;
 #[cfg(target_arch = "wasm32")]

apps/figcraft-web/src/web.rs

@@ -32,6 +32,15 @@ pub fn start() {
             log::error!("missing <canvas id=\"{CANVAS_ID}\">");
             return;
         };
+        // Host modes (`craft-web-host`): `?host=parent`, a same-origin page framing FigCraft, opens
+        // documents in it and stores what it saves (`host`); unframed there is no parent, so that URL
+        // on its own stays the normal app with downloads. `data-host="page"` on the canvas opts a
+        // page in instead: it runs FigCraft in its own document and talks over DOM `CustomEvent`s on
+        // the canvas.
+        let bridge = crate::host::Bridge::connect(&canvas);
+        let app_bridge = bridge.clone();
+        // Files the host sends, on their way into the app's own open queue each frame.
+        let opens: crate::host::OpenQueue = std::rc::Rc::default();
         let mut options = eframe::WebOptions::default();
         // `?webgl`: force the WebGL2 backend (troubleshooting, and headless browsers whose WebGPU
         // adapter request returns nothing).
@@ -44,12 +53,15 @@ pub fn start() {
             .start(
                 canvas,
                 options,
-                Box::new(|cc| {
+                Box::new(move |cc| {
                     if let Some(rs) = &cc.wgpu_render_state {
                         log::info!("figcraft-web: wgpu backend {:?}", rs.adapter.get_info().backend);
                     }
                     let reduce_motion = web_sys::window().and_then(|w| w.match_media("(prefers-reduced-motion: reduce)").ok().flatten());
-                    let mut session = Session::new();
+                    // Host mode: the host sends the file to edit, so start with no document (the
+                    // home screen), as the desktop app does without a file; otherwise the session
+                    // starts with one new document.
+                    let mut session = if app_bridge.is_some() { Session::empty() } else { Session::new() };
                     // The host names its own server: the default for sharing, codes and the team list.
                     if let Some(server) = page_meta("figcraft-server").as_deref().and_then(crate::query::page_server) {
                         session.prefs.publish_server = server;
@@ -60,11 +72,18 @@ pub fn start() {
                     // whatever arrives on the socket wakes the page for a frame.
                     let ctx = cc.egui_ctx.clone();
                     session.live.install(Box::new(figcraft_collab_net::NetLink::new(std::sync::Arc::new(move || ctx.request_repaint()))));
-                    let mut fig = FigApp::new(session, Box::new(WebServices { reduce_motion, ctx: cc.egui_ctx.clone() }));
+                    let mut fig = FigApp::new(session, Box::new(WebServices { reduce_motion, ctx: cc.egui_ctx.clone(), host: app_bridge.clone() }));
                     fig.note_recovered(recovered);
                     if let Err(e) = crate::pasted::install(cc.egui_ctx.clone()) {
                         log::error!("couldn't listen for pasted images: {e:?}");
                     }
+                    // `?author=`: the host's name for the user signs this visit's comments and board
+                    // notes (nothing is stored in the browser, so nothing needs keeping).
+                    if app_bridge.is_some()
+                        && let Some(author) = query_param("author")
+                    {
+                        crate::host::Bridge::set_author(&mut fig, &author);
+                    }
                     // `#join=<link>`: join that session, as opening an invite link does on the desktop.
                     let hash = web_sys::window().and_then(|w| w.location().hash().ok()).unwrap_or_default();
                     if let Some(link) = crate::query::join_link(&hash) {
@@ -78,10 +97,21 @@ pub fn start() {
                             log::error!("couldn't install window.figcraft: {e:?}");
                         }
                     }
-                    Ok(Box::new(WebShell { fig }))
+                    // The host's files arrive on the app's own open path (a dropped file's).
+                    if let Some(bridge) = &app_bridge {
+                        bridge.listen(opens.clone(), cc.egui_ctx.clone());
+                    }
+                    Ok(Box::new(WebShell { fig, host: app_bridge, opens }))
                 }),
             )
             .await;
+        // Ready only once the runner is up: starting can still fail after the app is made.
+        if let Some(bridge) = &bridge {
+            match &result {
+                Ok(()) => bridge.post_ready(),
+                Err(e) => bridge.post_failed(&format!("{e:?}")),
+            }
+        }
         if let Some(el) = document.get_element_by_id(LOADING_ID) {
             match result {
                 Ok(()) => el.remove(),
@@ -141,20 +171,45 @@ fn query() -> String {
     web_sys::window().and_then(|w| w.location().search().ok()).unwrap_or_default()
 }
 
+fn query_param(key: &str) -> Option<String> {
+    web_sys::UrlSearchParams::new_with_str(&query()).ok()?.get(key)
+}
+
 struct WebShell {
     fig: FigApp,
+    /// The host bridge, when the page hosts the app (`?host=parent` or `data-host="page"`).
+    host: Option<crate::host::Bridge>,
+    /// Files the host sent, waiting to join the app's own open queue.
+    opens: crate::host::OpenQueue,
 }
 
 impl eframe::App for WebShell {
     // eframe runs `logic` for visible tabs and, with only `run_logic`, for hidden ones: keep
     // autosave/live/control deadlines moving without a paint. `FigApp::ui` does not repeat it.
-    /// Run the browser shell's eframe logic callback: guard `background_tick` so hidden tabs
-    /// still advance autosave, live and control deadlines without painting. `FigApp::ui` does
+    /// Run the browser shell's eframe logic callback: hand the host's files to the app's open
+    /// queue, guard `background_tick` so hidden tabs still advance autosave, live and control
+    /// deadlines without painting, and report unsaved changes to the host. `FigApp::ui` does
     /// not repeat it.
     fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
         // Every frame, hidden or not, starts here: what the last one left is what a panic keeps.
         UNSAVED.with(|u| u.try_borrow_mut().map(|mut u| u.follow(&self.fig.session))).ok();
+        // Files the host sent join the app's own open queue (a dropped file's): the same
+        // "Opening as a new file" card, and `file.open` with the contents once read.
+        for (name, bytes) in std::mem::take(&mut *self.opens.borrow_mut()) {
+            let read: figcraft_ui_egui::ReadFuture = Box::pin(std::future::ready(Ok(bytes)));
+            self.fig.ui.pending_opens.push(figcraft_ui_egui::pending_open::PendingOpen {
+                label: name.clone(),
+                params: serde_json::json!({ "name": name }),
+                command: "file.open",
+                target: None,
+                read: Some(read),
+            });
+        }
         figcraft_ui_egui::windows::guard(&mut self.fig, ctx, |fig| fig.background_tick(ctx));
+        // The host hears when unsaved changes appear or go away (crate::host).
+        if let Some(bridge) = &self.host {
+            bridge.set_dirty(self.fig.session.docs.iter().any(|d| d.is_dirty()));
+        }
     }
 
     fn raw_input_hook(&mut self, ctx: &egui::Context, raw_input: &mut egui::RawInput) {
@@ -182,12 +237,15 @@ impl eframe::App for WebShell {
 
 /// Browser services. Files are opened and imported through the browser's file picker, which hands
 /// over their contents (pickers that need a path return nothing, the trait's defaults); files are
-/// saved as downloads. Copies go to the system clipboard through egui's output; pastes arrive as
-/// paste events with their text or image (a page can't read the clipboard when it likes).
+/// saved as downloads, or handed to the host page in host mode. Copies go to the system clipboard
+/// through egui's output; pastes arrive as paste events with their text or image (a page can't
+/// read the clipboard when it likes).
 struct WebServices {
     /// `prefers-reduced-motion: reduce` (it follows the setting while the page is open).
     reduce_motion: Option<web_sys::MediaQueryList>,
     ctx: egui::Context,
+    /// The host bridge in host mode: files are handed over instead of downloaded ([`crate::host`]).
+    host: Option<crate::host::Bridge>,
 }
 
 impl Services for WebServices {
@@ -204,11 +262,15 @@ impl Services for WebServices {
     fn downloads(&self) -> bool {
         true
     }
-    /// A Blob behind a temporary `<a download>` link, clicked and removed.
+    /// A Blob behind a temporary `<a download>` link, clicked and removed; in host mode the file
+    /// goes to the host page instead ([`crate::host`]).
     fn download(&mut self, name: &str, bytes: &[u8]) -> bool {
         if crate::api::capture(name, bytes) {
             return true;
         }
+        if let Some(bridge) = &self.host {
+            return bridge.post_save(name, bytes);
+        }
         match download(name, bytes) {
             Ok(()) => true,
             Err(e) => {

contributors/people.toml

@@ -101,3 +101,6 @@ sync_github_name = true
 
 [people.aleksei-suholita]
 real_name = "Oleksii Sukholita"
+
+[people.helenkwok]
+real_name = "Helen Kwok"

packaging/web/README.md

@@ -107,6 +107,104 @@ Local test: `python3 -m http.server 8767` inside the folder, then open http://lo
   (`allow-popups` lets Help links open in a new tab).
 - Don't send `X-Frame-Options: DENY` or a `frame-ancestors` CSP that excludes the embedding page.
 
+## Host mode (`?host=parent`, or the page's own document)
+
+A page can embed FigCraft so that it hands files over instead of downloading them and reports
+unsaved changes. Two opt-in transports carry the same messages:
+
+- **`?host=parent`** on the iframe's URL (`https://example.com/figcraft/?host=parent`): a
+  **same-origin** framing page talks to the app over `postMessage`. Opened outside an iframe, the
+  URL gives the normal app with downloads; with a parent on another origin there is no host mode
+  either (messages to another origin are dropped silently, so saves would be lost while the
+  document looked saved).
+- **`data-host="page"`** (the exact value `page`) on the canvas: a page that loads the module into
+  its own document gets the same behaviour over DOM `CustomEvent`s on the canvas, with no iframe
+  (see below).
+
+| Message | Direction | Fields |
+|---|---|---|
+| `figcraft:ready` | app → page | `version`, `appVersion`: the app is running and listening; send a file now |
+| `figcraft:open` | page → app | `name`, `bytes` (an `ArrayBuffer` or `Uint8Array`): open like File › Open (a payload over the browser open limit of 512 MB is refused; anything malformed is ignored) |
+| `figcraft:save` | app → page | `name`, `saveAs`, `bytes` (a transferred `ArrayBuffer`): every file the app would otherwise download. The page stores it and reports failures itself. `saveAs` says whether the file becomes the document's file: `false` after Save of the file the page sent, under its own name; `true` for a document file (`.figcraft`, `.json`) under a name the page didn't send — Save As, or a Save of a document the page never sent — after which the next Save carries that name with `false`; `false` for copies and exports that don't become the document (rendered images, SVG, PDF, `.fig` copies, the variables exports) |
+| `figcraft:dirty` | app → page | `dirty`: unsaved changes appeared or went away |
+| `figcraft:failed` | app → page | `error`: the app couldn't start (no WebGPU or WebGL2, for example) |
+
+Files reach the page through the app's download service, the path this web build saves by: Save As
+(and a Save of a document with no file yet), the `.fig` copy, the export panel and its dialog,
+Export frames as PDF, plugin output and the variables export (Variables panel ▸ Export…). In host
+mode each arrives as `figcraft:save` instead of a download.
+
+In host mode the app starts with no document (the home screen), so the page sends the file to edit
+and guards leaving the page while changes are unsaved. `&author=` on the URL names the user for
+comments and board notes.
+
+### Same-document host mode
+
+The host application loads the wasm-bindgen module itself and gives FigCraft one of its own
+canvases, so there is no iframe and no `?host=parent`. It opts in with `data-host="page"` on that
+canvas — the exact value `page` — and the canvas keeps the id the app looks up
+(`id="figcraft_canvas"`):
+
+```html
+<canvas id="figcraft_canvas" data-host="page" style="width: 100%; height: 720px; display: block;"></canvas>
+```
+
+The page and the app then talk with DOM `CustomEvent`s on the canvas instead of `postMessage`. The
+app dispatches the same messages it would post to a parent — `figcraft:ready`, `figcraft:save`,
+`figcraft:dirty`, `figcraft:failed` — with the message fields (without the type) as the event's
+`detail`, and it opens a document when the page dispatches a `figcraft:open` event with
+`detail: { name, bytes }`. Events do not bubble, so listen on the canvas itself (two editors on
+one page can't hear each other).
+
+Add the listeners before `init`: the app announces itself with `figcraft:ready` while `init` is
+still running, and a file sent in reply would otherwise be missed.
+
+```js
+import init from "./figcraft-web-<hash>.js"; // the wasm-bindgen glue shipped with the app
+
+const canvas = document.getElementById("figcraft_canvas");
+
+canvas.addEventListener("figcraft:ready", async () => {
+  // The app is listening; hand it a document now, if you have one.
+  const bytes = await documentBytes(); // an ArrayBuffer or Uint8Array
+  canvas.dispatchEvent(new CustomEvent("figcraft:open", {
+    detail: { name: "Poster.figcraft", bytes },
+  }));
+});
+
+// Every file FigCraft would otherwise download arrives here.
+canvas.addEventListener("figcraft:save", (event) => {
+  const { name, saveAs, bytes } = event.detail; // bytes is an ArrayBuffer
+  // Store the file under `name`; `saveAs` says whether it becomes the document's file.
+  // Report your own errors.
+  storeFile(name, bytes, saveAs);
+});
+canvas.addEventListener("figcraft:dirty", (event) => {
+  unsaved = event.detail.dirty; // warn before leaving, as you like
+});
+canvas.addEventListener("figcraft:failed", (event) => {
+  showError(event.detail.error); // the app couldn't start
+});
+
+await init({ module_or_path: "./figcraft-web-<hash>_bg.wasm" });
+```
+
+- Saves are not downloads in this mode: the `bytes` in `figcraft:save` hold the file, and the host
+  decides where it goes.
+- `?author=` on the page's URL still names the user for comments and board notes.
+- An unframed page that uses `?host=parent` keeps the normal app with downloads.
+  `data-host="page"` turns this mode on only when `?host=parent` is absent: if `?host=parent` is
+  present it takes precedence, so a same-origin framed page uses the parent bridge, while an
+  unframed or cross-origin page gets no bridge and keeps normal downloads.
+
+The messages and both transports are the shared contract of [`craft-web-host`](https://github.com/storytold/craft-libs/tree/main/crates/web-host) (storytold/craft-libs#420), the same for every Craft app: its README lists every message, including `saved`, with the compatibility notes. In `figcraft:ready`, `version` is the contract's (`"1"`) and `appVersion` is this app's release. FigCraft reads bytes, so a host sends `bytes`, not a `File`.
+
+### Trust and limits
+
+- **Who is trusted.** In page host mode the page and FigCraft share one document, so any script on the page can drive the app: open files in it and receive what it saves. Use this mode only for a page you control. The iframe mode (`?host=parent`) answers only the parent window, on the page's own origin.
+- **Files from the host are untrusted input.** An opened file goes through the same reading as one picked with File ▸ Open or dropped on the window, with the same format limits; before it is copied into the app's memory, its size is checked against the host open limit (512 MB) and a larger file is refused, and a name is cut to 255 characters.
+- **The event and message names are the interface.** `figcraft:ready`, `figcraft:open`, `figcraft:save`, `figcraft:dirty` and `figcraft:failed`, and the fields they carry (the same as the `?host=parent` messages), stay stable; changing one is a breaking change.
+
 ## Renderer selection and fallback flags
 
 FigCraft renders with wgpu. It uses **WebGPU** when the browser has it and falls back to