Tidigar share link specification

Status: public pre-release specification, version 1. It defines how any tool, script or AI agent can build a link that opens a complete, editable Tidigar roadmap. The link carries the whole roadmap itself, so nothing is uploaded, nothing is stored on a server and no account is needed.

The keywords MUST, MUST NOT, SHOULD and MAY are normative. The roadmap model, its field rules and limits are defined in the Tidigar Roadmap Interoperability Specification; this document only defines the compact link encoding.

Links are shared through the public opener:

https://open.tidigar.com/s#s=1.<data>

It opens the Tidigar web app with the roadmap, or the Tidigar app when it is installed and claims the link. The opener is not deployed yet; until it is, https://app.tidigar.com/#s=1.<data> opens the same roadmap in the web app.

Why links are small

A whole share link is at most 2,000 characters. That is a deliberate limit, not a technical accident: a shared roadmap is a small, useful starting plan that fits in a chat message, an email, a blog post or a QR code, and it opens anywhere Tidigar runs. Larger roadmaps are shared as project files.

Link format

https://open.tidigar.com/s#s=1.<data>

• The fragment starts with s=, the format version 1 and a dot.
• <data> is the payload JSON, UTF-8 encoded, compressed with raw DEFLATE (RFC 1951, no zlib or gzip header) and encoded as base64url without padding (RFC 4648 §5).
• The fragment including s=1. MUST be at most 1,900 characters. An encoder MUST refuse a larger roadmap rather than drop content.
• The fragment is never sent to a server by browsers, so the roadmap stays between the sender and the recipient.

A decoder MUST reject another version, a longer fragment, characters outside A–Z a–z 0–9 - _, data that does not inflate, more than 262,144 inflated bytes, invalid JSON or a payload that does not describe a valid roadmap. It MUST NOT open a partial roadmap.

Payload

The payload is one JSON object. Records have no IDs: they refer to each other by position. Two kinds of numbers appear:

• An index is a 0-based position in a list.
• An option number picks an option of a dimension: 0 means no option, 1 the first option, 2 the second, and so on.

Dates are whole days from January 1 of y; negative values are earlier. A length is the number of days from start to the inclusive end, so 0 is a single day. Colors are six hexadecimal digits without #.

Missing lists are empty. At most 20 dimensions with 100 options each.

Activity tuple

[title, start, length, description, progress, values, dependsOn]

Trailing default positions MAY be left out, and trailing 0 entries in values MAY be left out. A missing value and 0 mean the same: no option.

Milestone and period tuples

[title, date, dependsOn]            milestone: dependsOn holds activity indices
[title, start, length, color]       period band

A milestone's date MUST be at least one day after the end of each activity it depends on. Titles are 1–180 characters.

View object

A view uses the saved-view fields of the model specification except id, projectId and hideTimelineLabels, with these changes:

Every other field keeps its model value, for example "view": "timeline", "resolution": "week" or "timelineStart": "2026-01-01". A field left out takes its model default, and encoders SHOULD leave defaults out.

Opening a link

Tidigar adds the opened roadmap to the recipient's own library at once and shows it in the initial view. A decoder builds a canonical project from the payload, gives the project and every record a new random UUID, and validates the result with every rule of the model specification. The copy is independent: editing it never changes the link or anyone else's copy. Tidigar remembers on each device which roadmap a link made, so opening the same link there again selects that copy instead of adding another. The initial view opens the roadmap but is not saved as a view of it.

Example

{
  "n": "Website relaunch",
  "y": 2026,
  "d": "A small example template.",
  "m": [
    [
      "Team",
      [
        ["Design", "4f7cff"],
        ["Development", "16a34a"]
      ]
    ]
  ],
  "i": [
    ["Content audit", 5, 11, "", 100, [1]],
    ["New design", 19, 27, "", 50, [1], [0]],
    ["Build and test", 49, 41, "", 0, [2], [1]]
  ],
  "s": [["Launch", 93, [2]]],
  "p": [["Summer break", 180, 34, "f59e0b"]],
  "o": {
    "view": "timeline",
    "color": 0,
    "group": 0,
    "resolution": "week",
    "timelineEnd": "2026-04-30"
  }
}

The roadmap has one dimension, Team. Content audit runs 2026-01-06 to 2026-01-17 for Design and is done; New design runs 2026-01-20 to 2026-02-16 after it; Build and test runs 2026-02-19 to 2026-04-01 for Development; the Launch milestone is on 2026-04-04; a Summer break band covers 2026-06-30 to 2026-08-03. It opens as a weekly timeline grouped and colored by Team through April.

One valid encoding of that payload is this fragment of 364 characters. Compressors differ, so another encoder MAY produce different data for the same payload.

s=1.PVC7bsMwDPwVgTNTyK-k9tbXVnRpgQ6GBzmmU6F6GLYctwjy76WEoFpE3B2P5F3AQQOf1C86kJjJqNUdvwDhF5pc5nuEgfkHsVhljKAfZSdDIhB_KtAdCy00bQsfpCwgF8-06JNjvBwPx3GEDiN2JuMnSy4wke1VUSro-CHo1P3kXWBSqHXQLKkwyxAAMymxzbpo8UabGG7WWY35IfJVorGVSfK4ajMI5QZeb2GXssYy2bAq75IRD1zSwNfbmXURuYhPCX9fraVZ9DOpbx50L7EoEcaqJtlDlHloLnDWtHEqQVsy2hHfdPTGz9BIhNPs1ylVMy3erEH7mPBGxIb_LS8uxhoD3slyV0i4Xv8A

Building a link

Python:

import base64, json, zlib

def share_fragment(payload):
    data = json.dumps(payload, ensure_ascii=False, separators=(",", ":")).encode("utf-8")
    deflate = zlib.compressobj(9, zlib.DEFLATED, -15)
    packed = deflate.compress(data) + deflate.flush()
    fragment = "s=1." + base64.urlsafe_b64encode(packed).decode("ascii").rstrip("=")
    if len(fragment) > 1900:
        raise ValueError("The roadmap is too large for a share link.")
    return fragment

JavaScript (browsers and Node.js 18 or later):

async function shareFragment(payload) {
  const stream = new Blob([JSON.stringify(payload)])
    .stream()
    .pipeThrough(new CompressionStream('deflate-raw'));
  const bytes = new Uint8Array(await new Response(stream).arrayBuffer());
  const base64 = btoa(String.fromCharCode(...bytes));
  const fragment = `s=1.${base64.replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '')}`;
  if (fragment.length > 1900) throw new Error('The roadmap is too large for a share link.');
  return fragment;
}

Before sharing, check the dates and dependencies against the rules above: a link whose roadmap is invalid does not open.