docs/specs/2026-09-11-snippets-design.md
238 lines · 11462 bytes
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 0054, 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, id);
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- `limits.max_snippets_per_user`, default unlimited, like
98 `max_repos_per_user`. Enforced on `snippet create`; admins are not
99 exempt.
100- Snippet bytes do not count toward `max_bytes_per_user`; that quota
101 measures repositories and LFS.
102
103File names match the release asset name pattern:
104`^[A-Za-z0-9][A-Za-z0-9._+-]{0,199}$`, so no slashes and no leading dot.
105
106`store.Snippet` carries the row plus `OwnerName`; `store.SnippetFile`
107carries `Name`, `Size` and `Content`. Store functions: `CreateSnippet`,
108`SnippetByPublicID`, `ListSnippets(ownerID, all bool, limit, cursor)`,
109`UpdateSnippet`, `DeleteSnippet`, `SetSnippetFile`, `RemoveSnippetFile`,
110`SnippetFiles`, `SnippetFile`. Hand-written SQL, as everywhere.
111
112## Commands
113
114All in `internal/control/snippet.go`, registered like every other noun.
115Reads set `ReadOnly`; the two commands that take a body set
116`ReadsStdin`; nothing is `SSHOnly`, so the JSON API reaches all of it.
117
118| command | usage |
119|---|---|
120| `snippet create` | `snippet create <filename> [--description <d>] [--visibility public\|unlisted\|private] < file` |
121| `snippet show` | `snippet show <id>` |
122| `snippet list` | `snippet list [<owner>] [--limit n] [--cursor c]` |
123| `snippet edit` | `snippet edit <id> [--description <d>] [--visibility <v>]` |
124| `snippet delete` | `snippet delete <id>` |
125| `snippet file set` | `snippet file set <id> <filename> < file` |
126| `snippet file get` | `snippet file get <id> <filename> > file` |
127| `snippet file remove` | `snippet file remove <id> <filename>` |
128
129Behaviour:
130
131- `create` reads stdin as the first file, refuses empty stdin, content
132 that is not valid UTF-8, or content over the limit (exit 2 with the
133 reason), and prints the id and the web URL. JSON: `{id, url, owner,
134 description, visibility, created_at, updated_at, files:[{name,size}]}`.
135- `show` prints the metadata and the file list with sizes. `--json`
136 includes each file's `content` so one API read returns the whole
137 snippet.
138- `list` with no argument lists the caller's snippets at every
139 visibility, newest first. With `<owner>` it lists that owner's public
140 snippets, or everything when the owner is the caller or an admin. An
141 unknown owner is exit 3. Paged with keyset cursors like `repo list`;
142 the JSON is `{items, next}`.
143- `edit` changes the description or the visibility, or both; neither
144 given is exit 2.
145- `file set` adds a file or replaces one by name, under the same checks
146 as `create`, and refuses the 65th file. `file remove` refuses to
147 remove the last file: a snippet always has one. `file get` writes the
148 content to stdout unchanged.
149- `delete` removes the snippet and its files.
150
151Access, in `internal/policy` beside the repository rules. Key scope needs
152no rule of its own: the dispatcher already refuses every control command
153to a key that is not `full`.
154
155- Read: the owner and admins for `private`; anyone, anonymous included,
156 for `unlisted` and `public`.
157- Write: the owner and admins.
158- A snippet the caller may not read is exit 3, never 4, so a private id
159 cannot be confirmed. A snippet the caller may read but not write is
160 exit 4.
161
162CLI: one `pass()` per command in `cmd/gitbay/main.go`. `snippet create`
163and `snippet file set` use `alwaysStdin` with a `stdinWhat` naming the
164file's bytes, as `release asset add` does. No `needsRepo`: the noun is
165not repository-scoped, and the repo argument is never inferred.
166
167## Web
168
169Routes live under `/{owner}/-/`, the pattern `/{owner}/-/labels` set: a
170hyphen cannot start a repository name, so nothing is shadowed and no
171word joins `internal/policy/names.go`.
172
173| method | path | handler |
174|---|---|---|
175| GET | `/{owner}/-/snippets` | list: the owner's public snippets; everything, marked by visibility, when the viewer is the owner or an admin |
176| GET | `/{owner}/-/snippets/new` | create form, `requireUser`, owner must be the viewer |
177| POST | `/{owner}/-/snippets/new` | dispatch `snippet create`, redirect to the snippet |
178| GET | `/{owner}/-/snippets/{id}` | the snippet: description, visibility, each file highlighted with a raw link |
179| GET | `/{owner}/-/snippets/{id}/raw/{name}` | `text/plain; charset=utf-8`, `X-Content-Type-Options: nosniff` |
180| POST | `/{owner}/-/snippets/{id}/edit` | dispatch `snippet edit` |
181| POST | `/{owner}/-/snippets/{id}/delete` | dispatch `snippet delete`, redirect to the list |
182| POST | `/{owner}/-/snippets/{id}/file` | dispatch `snippet file set` with the textarea on stdin |
183| POST | `/{owner}/-/snippets/{id}/file/remove` | dispatch `snippet file remove` |
184
185An id under the wrong owner is 404. Private snippets are 404 to anyone
186but the owner and admins, unlisted ones render for anyone with the URL.
187Files are rendered through the existing `highlight(path, data)` by
188extension; `.md` and `.org` are highlighted as source, not rendered as
189markup, since a snippet is a paste rather than a document. Each file
190heading links to its raw route.
191
192Forms are on the snippet page for the owner: a textarea per file posting
193`file`, a remove button per file, an add-file form (name and textarea),
194a description and visibility form, and delete. All POSTs go through
195`checkOrigin` and `requireUser`, and answer through `done`, so a refusal
196returns to the page with the message and a missing snippet is the 404
197page.
198
199The owner page shows a `snippets` link below the repository list
200when the owner has a public snippet, or when the viewer is the owner.
201
202Templates: `snippets.html`, `snippet.html`, `snippetnew.html`. Stylesheet
203additions in `static/style.css` only where an existing class does not
204fit; the file blocks reuse the blob page's classes.
205
206## Testing
207
208`e2e/snippet_test.go`, over ssh with the real binary:
209
210- create prints an id of 12 hex characters and a URL; `show` and `file
211 get` round-trip the content byte for byte; `--json` on `show` carries
212 `content`.
213- visibility, from a second account and from anonymous HTTP: private is
214 exit 3 and 404 to the other account, unlisted is readable by id and
215 absent from `snippet list <owner>`, public is listed; the owner's own
216 `snippet list` shows all three.
217- `file set` replaces, `file remove` refuses the last file, the 65th
218 file is refused, non-UTF-8 and oversize bodies are refused with exit 2.
219- `edit` moves visibility and the listing follows.
220- `delete` then `show` is exit 3; deleting the user cascades the rows.
221- the other account cannot `edit`, `file set` or `delete` (exit 4 on an
222 unlisted snippet, exit 3 on a private one).
223
224`e2e/snippetweb_test.go`: the list and snippet pages render, raw is
225`text/plain` with nosniff, the create form makes a snippet, the file and
226edit forms change it, delete removes it, and the owner page carries the
227link. The existing coverage tests hold the rest: the CLI table, the
228`ReadsStdin` flag, and that every `ReadOnly` command writes nothing.
229
230## Documentation
231
232- `.gitbay/wiki/Users.org`: a `* Snippets` section after Pages.
233- `.gitbay/wiki/Parity.org`: rows for `snippet create, edit, delete`,
234 `snippet show, list`, `snippet file set, get, remove`; `cli` yes, `web`
235 yes, `ios` no.
236- `CHANGELOG.org`: the v1.20.0 entry.
237- `.gitbay/wiki/Admin.org`: `max_snippet_bytes` beside `max_asset_bytes`
238 in the limits list.