Shell: Tab completes a path on the SD card (#67)

Past the command's name, Tab completes the word being typed as a path: a
folder keeps its slash to go on from, a file completed whole gets a space,
several candidates are listed. Any case typed, the name's own is taken.
After a file command the first slash is understood (`cat no` is /no).
The folder is read on the storage task, bounded to 400 entries looked at
and 24 candidates.

489 host tests (2 new). Checked on the device: a folder, a file inside it,
several candidates, no slash, another case, nothing matching.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EhqxQ49eCju4CzKYNjZzwT

site/content/dev/milestones/s1.md

@@ -157,7 +157,7 @@ The console's commands could only be typed on a PC: over USB, or over Wi-Fi with
 | Q205 | **Trusted like USB serial**, not like the network: `debug on` and `debug token` work from it, as they do in Settings. The token is never shown. |
 | Q206 | *Revised the same day, after trying it.* **It shows the replies to its own commands, and only those.** The console knows who each line is printed for (`Console::Origin`): a command run from the Shell prints as the Shell's, and so does what answers it later from another task, which notes who asked and takes it back when it prints (`ls`, `tasks`, `du`, `cp`, `update check`, `sd list`, `screenshot`, `gemini get`). What USB or the Debug Console asked for, and the system's own lines, are not the Shell's. **Ctrl+b shows everything** instead. The first version kept whatever was printed in the ten seconds after a command, which was a guess, and a noisy one. |
 | Q207 | **Nothing while it's closed.** Open, a 4 KB ring of the console's and up to 4 KB of lines; both go when the App is left, with the list of commands for Tab. |
-| Q208 | Enter runs the line; Fn with up and down recalls the last 16; Alt with up and down scrolls back; **Tab completes the command's first word** from the firmware's `help` text. Paths aren't completed. |
+| Q208 | Enter runs the line; Fn with up and down recalls the last 16; Alt with up and down scrolls back. **Tab completes** the command's first word, from the firmware's `help` text, and *(added the same day)* **past it a path on the SD card**: a folder keeps its slash to go on from, a file completed whole gets a space, several candidates are listed. Whatever the case typed, the name's own is taken, since the card doesn't tell them apart. After a file command the first slash is understood (`cat no` is `/no`). A name with a space in it isn't completed. |
 | Q209 | *Revised the same day.* **`rm` is Unix's, with a question.** A folder needs `-r`, here and over the consoles (where `rm <folder>` used to remove it with what was in it). In the Shell, a file, or a folder with something in it, is asked about unless `-f` (`-rf`, `-r -f`); an empty folder with `-r` goes without a word; what `rm` would refuse anyway, it refuses itself. Over the consoles nothing is asked: scripts delete as before. **`screenshot [seconds]`** saves the screen as a PNG in `/screenshots`, now or after a pause, since from the Shell "now" is the Shell. `get`, `put`, `coredump get` and `reset` answer `Debug Console only`. |
 | Q210 | Commands are echoed as `> command` into the console, so a session reads the same from afar. **A token being set is not echoed.** |
 | Q211 | **Not in Safe Mode**, which starts no Apps: issue #77. |
@@ -172,7 +172,8 @@ The console's commands could only be typed on a PC: over USB, or over Wi-Fi with
 - **`info` says which App is in front** (`app: Shell`): so that a hand driving the device from afar can look before it types.
 - **`screenshot`** writes the PNG a row at a time with no buffer: 8-bit indexed colour, the 256 colours of RGB332 as the palette, the pixels in one stored deflate block (`lib/files/src/png_rgb332.h`, 4 tests). 33,383 bytes for the 240 x 135 screen. A Toast says so once it is on the card, so the Toast is never in the picture.
 - **The `help` text lost its shorthand** (`update check | list | status` is written out), since Tab reads its first words from there.
-- **Cost:** 16 KB of flash, 56 bytes of static RAM. Open: 7 KB of heap (107.6 KB free before, 100.7 with it open, 106.1 after leaving).
+- **Tab on a path** reads the folder on the storage task while the main loop waits, so it is bounded: 400 entries looked at, 24 candidates given back, and `...` after the list when there were more.
+- **Cost:** 21 KB of flash, 96 bytes of static RAM. Open: 7 KB of heap (107.6 KB free before, 100.7 with it open, 106.1 after leaving).
 
 ### What went wrong while building it
 
@@ -196,6 +197,7 @@ Two changes came of it. The Shell now **queues** its line and the main loop runs
 | `rm -r` on an empty folder | Removed, no question |
 | `rm -r` on a folder with files | Asks; Cancel leaves it. `rm -rf` removes it without asking |
 | `rm` on a file | Asks; Delete removes it |
+| Tab on a path | `ls /no` becomes `ls /notes/`, and again, with one note in it, the note's whole name and a space. `ls /g` lists `gemini/  gnss/`. `cat no` becomes `cat /notes/`. `rm -r /CAP` becomes `rm -r /captures/`. `ls /zz` stays as it is |
 | `No`, Tab, Enter | Completes to `Notes ` and opens Notes. `Shell` from the Debug Console opens the Shell |
 | `screenshot 4`, then Home | The picture, taken four seconds later, is of the Launcher: the pause works, and the Toast isn't in it |
 | `quit` | Back to the Launcher, and the memory comes back |

site/content/guide/shell.md

@@ -23,7 +23,7 @@ Type a command and press <kbd>Enter</kbd>. `help` lists them all; the [command r
 | `update check` | Whether a newer release exists |
 | `lora status` | What the radio is set to and what it has heard |
 
-- <kbd>Tab</kbd> **completes** the command's name. If several fit, it lists them.
+- <kbd>Tab</kbd> **completes** what you are typing: the command's name first, then **a path on the SD card**. `ls /no` and Tab gives `ls /notes/`; Tab again goes on inside the folder. If several names fit, it completes as far as they agree and lists them. You can type the name in any case, and after a file command you can leave out the first slash: `cat no` and Tab gives `cat /notes/`. A name with a space in it isn't completed.
 - <kbd>Fn</kbd> with up and down brings back **lines you typed before**.
 - <kbd>Alt</kbd> with up and down **scrolls back** through what was printed.
 - `clear` empties the screen, and `quit` (or Back) leaves.