# G1 — Gemini client

**Goal:** browse Geminispace from the Cardputer: fetch and read gemtext over TLS, follow links, answer input prompts, keep bookmarks, and save pages to the SD card to read later, offline. A side milestone between M2 and M3, tagged v0.5.0 when done.

Gemini (geminiprotocol.net): one request per TLS connection on port 1965, the request is the URL and CRLF, the response a `<status> <meta>` header line, then the body. Most capsules use self-signed certificates: trust on first use is the norm.

## Decisions (design round 2026-10-05)

| # | Decision |
|---|---|
| Q70 | A milestone of its own, **G1**, before M3: plan, tests first, measured on the device, tagged v0.5.0. |
| Q71 | **TOFU:** the first certificate seen for a host is pinned (SHA-256, in NVS). If it changes, the page isn't shown; a dialog shows both fingerprints and asks whether to trust the new one. Self-signed or expired certificates are fine; only a change counts. |
| Q72 | Responses: 1x input (11 hidden, for passwords), 2x content, up to 5 redirects (3x), 4x/5x errors with the server's message. 6x (client certificates): "not supported". |
| Q73 | `text/gemini` is rendered, other `text/*` shown as plain text. Anything else can be saved to `/gemini/downloads/`, not shown. |
| Q74 | Up to **64 KB on screen**, larger pages truncated with a notice. Saving streams to the card, so a larger page is saved whole. |
| Q75 | Gemtext rendering: text wrapped to the 40-column screen; `#`/`##`/`###` headings in bold and accent; `*` lists with bullets; `>` quotes indented and muted; preformatted blocks unwrapped, Left/Right to scroll; `=>` links with their label, numbered. |
| Q76 | Up/Down scroll; Tab and Shift+Tab move between links; Enter follows; Backspace goes back; `g` opens the address line. Links to other protocols show their URL and aren't followed. |
| Q77 | Back history of 20 URLs in RAM, with scroll positions; going back refetches (or reopens a Saved Page). **Bookmarks** in `/gemini/bookmarks.gmi` (a gemtext page, shown on the start page); `b` adds the current page. Without a card, a built-in start page. |
| Q78 | Start page: bookmarks, then Saved Pages, then defaults: geminiprotocol.net, a search engine (kennedy.gemi.dev), an aggregator (Cosmos; Antenna was down when measured). |
| Q79 | UTF-8 decoded; characters outside the Latin-1 fonts shown as `?`. |
| Q80 | IRC and Gemini can run together: each fetch opens one connection, reads and closes it. If there isn't memory for a second TLS connection, the fetch fails with a clear message and IRC is untouched. Measured in step 1. |
| Q81 | Debug aid: `gemini get <url>` prints the status, MIME type, size, certificate fingerprint and the first lines. URL resolution (RFC 3986), the response header and gemtext parsing are host-tested. |
| Q82 | `s` saves the page on screen as a **Saved Page**: `/gemini/saved/<host>/<path>.gmi`, the gemtext as received plus a first line with its URL and save date. Saving again replaces it, and says so. |
| Q83 | `S` saves the page and the pages it links to, one level deep: gemtext only, same host only, at most 30 pages, in the background with a progress Toast. |
| Q84 | The start page lists Saved Pages, newest first, grouped by capsule; they open with no network. In a Saved Page, a link to another Saved Page opens the saved copy; other links fetch online if Wi-Fi is up, or say "not saved, offline". A Saved Page shows when it was saved; `r` refreshes it. |
| Q85 | Saved Pages are deleted from the App only (`d`, with confirmation), never by Storage Clean-up's age rules, like Notes. |

## Measured (step 1)

- `gemini://geminiprotocol.net/`: `20 text/gemini`, 1,184 bytes, TLS handshake 0.7–1.1 s, whole fetch 0.7–1.1 s; kennedy.gemi.dev 1.9 s. The fetch task's stack peaks at about 3.6 KB of 6.
- **Heap, Debug Build, IRC connected over TLS:** about 68 KB free before a fetch. After the handshake the fetch holds about 32 KB (36–40 KB left); the handshake itself (certificate chain parsed with the 16 KB receive buffer allocated) dips to about **24 KB** for a second or two. Nothing leaks: the heap after matches the heap before.
- Antenna (`warmedal.se`) doesn't answer, from the PC either; the default aggregator becomes Cosmos (`gemini://skyjake.fi/~Cosmos/`, which redirects to `cosmos.skyjake.fi`).

## Done when

- `gemini get gemini://geminiprotocol.net/` prints the header, size and fingerprint on the console.
- The Gemini App opens the start page, follows links (relative ones included), goes back, and follows redirects.
- An input prompt (e.g. a search) takes a query and shows the results.
- A changed certificate stops the page and asks.
- `s` saves a page, `S` a page and its links; with Wi-Fi off, Saved Pages open and their saved links work.
- Bookmarks are added with `b` and listed on the start page.
- With IRC connected over TLS, a fetch still works, and the free heap stays above 40 KB.

## Work breakdown

1. **Two TLS connections:** measure the heap with IRC connected while a Gemini fetch runs.
2. **Parsers** (host-tested): URL parsing and relative resolution, the response header, gemtext lines.
3. **Fetch** on its own task, with TOFU and `gemini get`.
4. **Gemini App:** rendering, scrolling, links, history, the address line.
5. **Input prompts, redirects, bookmarks, downloads.**
6. **Saved Pages,** then saving with linked pages.