zzstoatzz.io
atproto tools in zig
zat.dev
sdk
atproto
zig
add readme, fix tid first-char validation
- add minimal README with install/usage
- tid: first char must have high bit 0x40 unset (only 2-7 allowed)
- add test for rejecting tids starting with a-z
ref: MarshalX/atproto string_formats.py
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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README.md
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README.md
···
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# zat
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zig atproto primitives. parsing utilities for TID, AT-URI, and DID.
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## status
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alpha (`0.0.1-alpha`). APIs are in `internal` module while we iterate.
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## install
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```zig
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// build.zig.zon
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.dependencies = .{
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.zat = .{
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.url = "https://tangled.sh/@zzstoatzz.io/zat/archive/main.tar.gz",
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.hash = "...", // zig build will tell you
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},
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},
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```
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## usage
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```zig
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const zat = @import("zat");
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// TID - timestamp identifiers
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const tid = zat.internal.Tid.parse("3jui7kze2c22s") orelse return error.InvalidTid;
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const ts = tid.timestamp(); // microseconds since epoch
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const clock = tid.clockId(); // 10-bit clock id
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// AT-URI - at://did/collection/rkey
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const uri = zat.internal.AtUri.parse("at://did:plc:xyz/app.bsky.feed.post/abc123") orelse return error.InvalidUri;
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const did = uri.did(); // "did:plc:xyz"
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const collection = uri.collection(); // "app.bsky.feed.post"
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const rkey = uri.rkey(); // "abc123"
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// DID - did:plc and did:web
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const d = zat.internal.Did.parse("did:plc:z72i7hdynmk6r22z27h6tvur") orelse return error.InvalidDid;
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const id = d.identifier(); // "z72i7hdynmk6r22z27h6tvur"
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const is_plc = d.isPlc(); // true
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```
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## why internal?
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new APIs start in `internal` and get promoted to root when stable. if you need bleeding edge, use `zat.internal.*` and expect breakage.
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src/internal/tid.zig
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src/internal/tid.zig
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//!
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//! tids encode a timestamp and clock id in a base32-sortable format.
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//! format: 13 characters using alphabet "234567abcdefghijklmnopqrstuvwxyz"
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//! - first 11 chars: 53-bit timestamp (microseconds since epoch)
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//! - last 2 chars: 10-bit clock identifier
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//! - first char must be 2-7 (high bit 0x40 must be 0)
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//! - remaining chars encode 53-bit timestamp + 10-bit clock id
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//!
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//! the encoding is designed to be lexicographically sortable by time.
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//! see: https://atproto.com/specs/record-key#record-key-type-tid
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const std = @import("std");
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···
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/// parse a tid string. returns null if invalid.
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pub fn parse(s: []const u8) ?Tid {
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if (s.len != 13) return null;
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// first char high bit (0x40) must be 0, meaning only '2'-'7' allowed
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if (s[0] & 0x40 != 0) return null;
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var result: Tid = undefined;
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for (s, 0..) |c, i| {
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// invalid chars
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try std.testing.expect(Tid.parse("0000000000000") == null);
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try std.testing.expect(Tid.parse("1111111111111") == null);
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// first char must be 2-7 (high bit 0x40 must be 0)
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try std.testing.expect(Tid.parse("a222222222222") == null);
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try std.testing.expect(Tid.parse("z222222222222") == null);
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}
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test "roundtrip" {