docs/specs/2026-09-11-snippets-design.md

  1# Snippets
  2
  3Closes #195 (ref #185). A snippet is a small set of named text files a
  4user owns, shares by URL, and edits in place: paste.sr.ht's paste with a
  5gist's mutability, without the git repository underneath.
  6
  7## Problem
  8
  9#185 walked a sourcehut user's day and found that sharing a log or a
 10fragment several times a week has no object here. Neither a repository
 11(too heavy for a log) nor an issue (wrong shape) covers it. #195 asks for
 12the feature rather than a FAQ entry declining it.
 13
 14## Decision
 15
 16A snippet is rows in SQLite: an owner, a description, a visibility, and
 17one or more named files with their content. It is created and edited
 18over SSH and the API, rendered and edited on the web through the same
 19control commands, and identified by an opaque id in a URL under the
 20owner.
 21
 22Decisions taken on the way, with the alternatives rejected:
 23
 24- **Store-backed, not a git repository.** A gist is a bare repository
 25  with a flag, cloneable and versioned, which would drag in a namespace
 26  decision, a receive-pack path that skips CI, issues and merge
 27  requests, and the whole repository policy surface. The use case is a
 28  log pasted from a terminal. If history is ever wanted the id and URL
 29  scheme below do not have to change.
 30- **Mutable, opaque id.** paste.sr.ht keys a paste on a hash of its
 31  content, so a typo fix changes the URL already shared. A random id
 32  keeps the URL; updating a file replaces it and no history is kept.
 33- **Three visibilities, default unlisted.** `public` is listed on the
 34  owner's page; `unlisted` is readable by anyone with the URL and listed
 35  nowhere; `private` is the owner's alone and answers 404 to everyone
 36  else, as a private repository does. Sharing a log wants unlisted,
 37  so that is the default when `snippet create` names none.
 38- **Users only.** Nothing in #195 or #185 asks for an org to own a
 39  snippet, and an org snippet would need a membership rule for writes.
 40- **Web writes in the same merge request.** The Parity rule lands only
 41  the triage loop on the web at once; the request here was parity in one
 42  go. Every form dispatches a control command through `runControlStdin`,
 43  so no rule lives in a handler.
 44- **Text only.** Content must be valid UTF-8. A snippet is read on a
 45  page and served raw as `text/plain`; a binary belongs in a release
 46  asset.
 47- **One file per command.** Stock OpenSSH carries one stdin stream, so
 48  `snippet create` takes one file and `snippet file set` adds the rest.
 49  A packed multi-file format on stdin would fail the stock-ssh
 50  constraint.
 51- **No `--yes` on delete.** `release delete --yes` guards assets that
 52  are gone for good; a snippet has nothing hanging off it and is a
 53  paste, not a release.
 54- **No events, audit rows, notifications, comments, search, Atom feed
 55  or explore listing.** Events are keyed on a repository. None of the
 56  rest was asked for.
 57
 58## Data
 59
 60Migration 0053, no rebuild:
 61
 62```sql
 63CREATE TABLE snippets (
 64    id          INTEGER PRIMARY KEY,
 65    public_id   TEXT NOT NULL UNIQUE,
 66    owner_id    INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
 67    description TEXT NOT NULL DEFAULT '',
 68    visibility  TEXT NOT NULL CHECK (visibility IN ('public','unlisted','private')),
 69    created_at  TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now')),
 70    updated_at  TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%fZ','now'))
 71);
 72CREATE INDEX snippets_owner ON snippets(owner_id, created_at);
 73
 74CREATE TABLE snippet_files (
 75    snippet_id INTEGER NOT NULL REFERENCES snippets(id) ON DELETE CASCADE,
 76    name       TEXT NOT NULL,
 77    content    BLOB NOT NULL,
 78    size       INTEGER NOT NULL,
 79    PRIMARY KEY (snippet_id, name)
 80);
 81```
 82
 83`public_id` is 12 lowercase hex characters from `crypto/rand` (48 bits),
 84generated on create and retried on a unique violation. It is global: the
 85CLI takes `<id>` alone, and the owner in the URL is for reading, not for
 86lookup.
 87
 88`updated_at` moves on every file or metadata write. Deleting a user
 89deletes their snippets through the cascade, as it does their keys.
 90
 91Limits:
 92
 93- `limits.max_snippet_bytes` in `config.toml`, per file, default
 94  1 MiB. Enforced on create and `file set` with the same
 95  `io.LimitReader(n+1)` shape as `release asset add`.
 96- 64 files per snippet, a constant in `internal/control/snippet.go`.
 97- Snippet bytes do not count toward `max_bytes_per_user`; that quota
 98  measures repositories and LFS.
 99
100File names match the release asset name pattern:
101`^[A-Za-z0-9][A-Za-z0-9._+-]{0,199}$`, so no slashes and no leading dot.
102
103`store.Snippet` carries the row plus `OwnerName`; `store.SnippetFile`
104carries `Name`, `Size` and `Content`. Store functions: `CreateSnippet`,
105`SnippetByPublicID`, `ListSnippets(ownerID, all bool, limit, cursor)`,
106`UpdateSnippet`, `DeleteSnippet`, `SetSnippetFile`, `RemoveSnippetFile`,
107`SnippetFiles`, `SnippetFile`. Hand-written SQL, as everywhere.
108
109## Commands
110
111All in `internal/control/snippet.go`, registered like every other noun.
112Reads set `ReadOnly`; the two commands that take a body set
113`ReadsStdin`; nothing is `SSHOnly`, so the JSON API reaches all of it.
114
115| command | usage |
116|---|---|
117| `snippet create` | `snippet create <filename> [--description <d>] [--visibility public\|unlisted\|private] < file` |
118| `snippet show` | `snippet show <id>` |
119| `snippet list` | `snippet list [<owner>] [--limit n] [--cursor c]` |
120| `snippet edit` | `snippet edit <id> [--description <d>] [--visibility <v>]` |
121| `snippet delete` | `snippet delete <id>` |
122| `snippet file set` | `snippet file set <id> <filename> < file` |
123| `snippet file get` | `snippet file get <id> <filename> > file` |
124| `snippet file remove` | `snippet file remove <id> <filename>` |
125
126Behaviour:
127
128- `create` reads stdin as the first file, refuses empty stdin, content
129  that is not valid UTF-8, or content over the limit (exit 2 with the
130  reason), and prints the id and the web URL. JSON: `{id, url, owner,
131  description, visibility, created_at, updated_at, files:[{name,size}]}`.
132- `show` prints the metadata and the file list with sizes. `--json`
133  includes each file's `content` so one API read returns the whole
134  snippet.
135- `list` with no argument lists the caller's snippets at every
136  visibility, newest first. With `<owner>` it lists that owner's public
137  snippets, or everything when the owner is the caller or an admin. An
138  unknown owner is exit 3. Paged with keyset cursors like `repo list`;
139  the JSON is `{items, next}`.
140- `edit` changes the description or the visibility, or both; neither
141  given is exit 2.
142- `file set` adds a file or replaces one by name, under the same checks
143  as `create`, and refuses the 65th file. `file remove` refuses to
144  remove the last file: a snippet always has one. `file get` writes the
145  content to stdout unchanged.
146- `delete` removes the snippet and its files.
147
148Access, in `internal/policy` beside the repository rules. Key scope needs
149no rule of its own: the dispatcher already refuses every control command
150to a key that is not `full`.
151
152- Read: the owner and admins for `private`; anyone, anonymous included,
153  for `unlisted` and `public`.
154- Write: the owner and admins.
155- A snippet the caller may not read is exit 3, never 4, so a private id
156  cannot be confirmed. A snippet the caller may read but not write is
157  exit 4.
158
159CLI: one `pass()` per command in `cmd/gitbay/main.go`. `snippet create`
160and `snippet file set` use `alwaysStdin` with a `stdinWhat` naming the
161file's bytes, as `release asset add` does. No `needsRepo`: the noun is
162not repository-scoped, and the repo argument is never inferred.
163
164## Web
165
166Routes live under `/{owner}/-/`, the pattern `/{owner}/-/labels` set: a
167hyphen cannot start a repository name, so nothing is shadowed and no
168word joins `internal/policy/names.go`.
169
170| method | path | handler |
171|---|---|---|
172| GET | `/{owner}/-/snippets` | list: the owner's public snippets; everything, marked by visibility, when the viewer is the owner or an admin |
173| GET | `/{owner}/-/snippets/new` | create form, `requireUser`, owner must be the viewer |
174| POST | `/{owner}/-/snippets/new` | dispatch `snippet create`, redirect to the snippet |
175| GET | `/{owner}/-/snippets/{id}` | the snippet: description, visibility, each file highlighted with a raw link |
176| GET | `/{owner}/-/snippets/{id}/raw/{name}` | `text/plain; charset=utf-8`, `X-Content-Type-Options: nosniff` |
177| POST | `/{owner}/-/snippets/{id}/edit` | dispatch `snippet edit` |
178| POST | `/{owner}/-/snippets/{id}/delete` | dispatch `snippet delete`, redirect to the list |
179| POST | `/{owner}/-/snippets/{id}/file` | dispatch `snippet file set` with the textarea on stdin |
180| POST | `/{owner}/-/snippets/{id}/file/remove` | dispatch `snippet file remove` |
181
182An id under the wrong owner is 404. Private snippets are 404 to anyone
183but the owner and admins, unlisted ones render for anyone with the URL.
184Files are rendered through the existing `highlight(path, data)` by
185extension; `.md` and `.org` are highlighted as source, not rendered as
186markup, since a snippet is a paste rather than a document. Each file
187heading links to its raw route.
188
189Forms are on the snippet page for the owner: a textarea per file posting
190`file`, a remove button per file, an add-file form (name and textarea),
191a description and visibility form, and delete. All POSTs go through
192`checkOrigin` and `requireUser`, and answer through `done`, so a refusal
193returns to the page with the message and a missing snippet is the 404
194page.
195
196The owner page shows a `snippets` link beside the repositories heading
197when the owner has a public snippet, or when the viewer is the owner.
198
199Templates: `snippets.html`, `snippet.html`, `snippetnew.html`. Stylesheet
200additions in `static/style.css` only where an existing class does not
201fit; the file blocks reuse the blob page's classes.
202
203## Testing
204
205`e2e/snippet_test.go`, over ssh with the real binary:
206
207- create prints an id of 12 hex characters and a URL; `show` and `file
208  get` round-trip the content byte for byte; `--json` on `show` carries
209  `content`.
210- visibility, from a second account and from anonymous HTTP: private is
211  exit 3 and 404 to the other account, unlisted is readable by id and
212  absent from `snippet list <owner>`, public is listed; the owner's own
213  `snippet list` shows all three.
214- `file set` replaces, `file remove` refuses the last file, the 65th
215  file is refused, non-UTF-8 and oversize bodies are refused with exit 2.
216- `edit` moves visibility and the listing follows.
217- `delete` then `show` is exit 3; deleting the user cascades the rows.
218- the other account cannot `edit`, `file set` or `delete` (exit 4 on an
219  unlisted snippet, exit 3 on a private one).
220
221`e2e/snippetweb_test.go`: the list and snippet pages render, raw is
222`text/plain` with nosniff, the create form makes a snippet, the file and
223edit forms change it, delete removes it, and the owner page carries the
224link. The existing coverage tests hold the rest: the CLI table, the
225`ReadsStdin` flag, and that every `ReadOnly` command writes nothing.
226
227## Documentation
228
229- `.gitbay/wiki/Users.org`: a `* Snippets` section after Pages.
230- `.gitbay/wiki/Parity.org`: rows for `snippet create, edit, delete`,
231  `snippet show, list`, `snippet file set, get, remove`; `cli` yes, `web`
232  yes, `ios` no.
233- `CHANGELOG.org`: the v1.20.0 entry.
234- `.gitbay/wiki/Admin.org`: `max_snippet_bytes` beside `max_asset_bytes`
235  in the limits list.