Links: Find in Folder… looks for missing linked files in a folder and its subfolders

Find in Folder… in Linked File Not Found and in the Links panel menu
looks in a folder the user picks, and in its subfolders, for the files
with the names of missing linked files, in any letter case. In the
Links panel menu it looks for the selected linked files when there are
any. It uses the folder search of the Missing Fonts dialog. Find
Linked Files lists each file it looks for with the files found for it.
A file with the size and contents saved with the link comes first. A
file of the saved size comes next when the link saved no hash or the
file is larger than 1 GB, and any other file of the name comes last.
Within each group, a file named in the same letter case comes first.
Then each file's folder names are compared with the saved path's, from
the innermost outward, up to the first one that differs, and a file
with more matching names comes before one with fewer. A file is chosen
when it is the only file found, or the only one with the saved
contents, and the user can choose another file or Don't Relink.

Relink relinks each file chosen, and each relink is one undo step.
With Copy into the document's folder, which shows for a saved
document, each image's file is copied next to the document first. The
file's name, then Name 2.png, Name 3.png and so on, are tried in turn
until one is free, which gets the copy, or is a file with the same
contents, which is used. A placed document is relinked where its file
is. The status line names the first file that fails to relink, and the
other files still relink. When Find Linked Files opens from Linked
File Not Found, the missing files left without a choice, and any that
fail to relink, go back to that dialog. On the web, Find in Folder… is
disabled in the Links panel menu, and links.findFiles can't start a
search.

- links.findFiles searches on separate threads and returns at once;
  links.findFiles {} reports the search, and {stop: true} stops it. It
  looks for at most 1,000 linked files at once: the active document's
  missing ones, or those of the objects it is given. It hashes a file
  only when a link of its name saved the file's size and a hash, and
  only when the file is 1 GB or smaller. It ends once every linked
  file has its same file, and it searches only the folders
  text.findFontFiles may search, with the same maxSeconds, depth and
  count limits.
- links.relink {copy} copies the file it is given into the saved
  document's folder and links images to the copy; a call that includes
  a placed document fails. Each name it writes is checked against the
  automation write root. text.addFontFiles and links.relink {copy}
  make their copies with fileio::copy_new, which never replaces a
  file. The text.addFontFiles params text and docs/mcp.md say which
  names are tried for a copy.
- vectorcraft-doc adds links::hash_reader, which hashes what a reader
  reads as hash_bytes hashes bytes.
- ui.findLinksInFolder is the Links panel's Find in Folder… for agents;
  docs/control-protocol.md lists the dialog's fields.

Docs: docs/mcp.md, docs/control-protocol.md, docs/target-app-parity.md.

docs/mcp.md

@@ -65,10 +65,10 @@ the suite) keep the agent to the folders you give it:
 
 - Every file a command reads must lie inside the **read root**: `open_file`, `file.place`, relinking and
   updating links, the images an SVG links to, swatch library, graphic style library and colour-profile loads, plug-ins,
-  `file.newFromTemplate`, preset imports, the folders `text.findFontFiles` searches.
+  `file.newFromTemplate`, preset imports, the folders `text.findFontFiles` and `links.findFiles` search.
 - Every file a command writes must lie inside the **write root**: `save_file`, `export`, the save and
   export commands, Export for Screens, Package, Export for Web, print to file, `screenshot {path}`,
-  library and preset saves to a path.
+  library and preset saves to a path, the copies `links.relink {copy}` makes.
 - `file.list {path}` (through `run_command`) lists a folder's files and folders, held to the read root like any read, so an agent can see what it was given (#1163).
 - Read and write access are separate. Give the same folder twice for both; a root left out grants none
   of its access (with only `--automation-read-root`, nothing can be written to disk, though `export` and
@@ -1934,6 +1934,24 @@ comes back to the front, following the same preference. `links.check` reports ev
 another file (or each at the file of its name in a folder); images keep their bounds, one undo step each. Without a
 file system (the web), linked images show their previews.
 
+`links.findFiles {folder}` looks in an absolute folder and its subfolders, on separate threads, for the files of the
+active document's missing links, or of the images and placed documents `ids` whatever their status, and returns at once
+with an `id` and the search's `state` (`searching` while it runs). It finds the files with each linked file's name, in
+any letter case, and lists them best first as `{path, size, match, caseDiffers?}`: `same` when the file has the size and
+hash saved with the link, `size` when it has the saved size and the link saved no hash (or the file is larger than 1 GB,
+which a search doesn't hash), else `name`. Within each kind, a file whose name has the link's letter case comes first.
+Then each file's folder names are compared with the saved path's, from the innermost outward up to the first one that
+differs, and a file with more matching names comes first; files that still tie are listed by path. `links.findFiles {}`
+returns the last search's state, and `{stop: true}` stops it. A search looks for at most 1,000 linked files, keeps the
+first 10 files of each one's name and up to 10 that are the same file, and ends once every linked file has its same
+file; it searches only the folders `text.findFontFiles` may search, with the same `maxSeconds`, depth and count limits.
+`links.relink {ids, path, copy: true}` copies the file into the saved document's folder and links images to the copy,
+never replacing a file there: the names `Name.png`, `Name 2.png` up to `Name 99.png` are tried in turn until one is
+free, which gets the copy (`copied`), or is a file with the same contents, which is used (`kept`). With `copy`, a call
+that includes a placed document fails and relinks nothing; placed documents are relinked without `copy`, where their
+files are. Find in Folder… in the Linked File Not Found dialog and in the Links panel menu (`ui.findLinksInFolder`) runs
+both. The web build has no folder search.
+
 Placed documents (a `.vectorcraft` file placed linked) work the same way: the document keeps the file's bytes and a
 preview (JPEG or PNG, 1 px per point, at most 1024 px a side), and a save writes the preview (Include Linked Files:
 the file); output reads the file again, or uses the preview with a warning when it is gone or changed.
@@ -1946,6 +1964,9 @@ the document; so does `object.expand`.
 {"name":"run_command","arguments":{"command":"links.check","params":{}}}
 {"name":"run_command","arguments":{"command":"links.relink","params":{"ids":[12],"path":"/new/photo.png"}}}
 {"name":"run_command","arguments":{"command":"links.update","params":{}}}
+{"name":"run_command","arguments":{"command":"links.findFiles","params":{"folder":"/Users/me/Archive"}}}
+{"name":"run_command","arguments":{"command":"links.findFiles","params":{}}}
+{"name":"run_command","arguments":{"command":"links.relink","params":{"ids":[12],"path":"/Users/me/Archive/2024/photo.png","copy":true}}}
 ```
 
 Placing a text file (`.txt`) sets it as area type: `file.place {path | name+dataBase64, text?: {characterSet?:
@@ -2898,8 +2919,9 @@ drive, are searched as any other folder is.
 `text.addFontFiles {files}` copies files that the session's last search found into VectorCraft's `Fonts` folder, then
 scans the fonts again, and type set in them redraws. It copies only regular `.ttf`, `.otf`, `.ttc`, `.otc`, `.woff`
 and `.woff2` files and suitcase fonts (with their resource fork), at most 256 MB a file and 1 GB in all, and lists any
-other file in `skipped`. It never replaces a file: a file with the same contents is kept (`kept`), and when another
-file has the name, the copy gets a number (`Name 2.otf`). Copy only fonts you own or are licensed to install. `command.batch` returns before a search ends; later requests over MCP or the control channel poll
+other file in `skipped`. It never replaces a file: the names `Name.otf`, `Name 2.otf` up to `Name 99.otf` are tried in
+turn until one is free, which gets the copy, or is a file with the same contents, which is kept (`kept`).
+Copy only fonts you own or are licensed to install. `command.batch` returns before a search ends; later requests over MCP or the control channel poll
 `text.findFontFiles {}`. `vectorcraft-cli run` stops the search when its last step ends. The web build has no Fonts
 folder and no folder search.