> ## Documentation Index
> Fetch the complete documentation index at: https://docs.deeda.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Template Variables

> What {{workflow_id}}, {{issue_ref}}, and {{your_arg}} are, who fills them, and how to trace them in analytics.

Anything wrapped in `{{ }}` inside a workflow string (like `task_template`)
is a **template variable**. You do not invent their values at write time —
Cadence fills them at dispatch. This page is the complete contract.

## Resolution order (exactly four steps)

When Cadence renders a template string it resolves each `{{name}}` in this
order — first match wins:

| Priority | Source                      | Examples                                                                     | Who provides the value                                                                  |
| -------- | --------------------------- | ---------------------------------------------------------------------------- | --------------------------------------------------------------------------------------- |
| 1        | **Fixed slots**             | `{{workflow_id}}`, `{{issue_ref}}`, `{{ticket.id}}`                          | Cadence, always. Never you.                                                             |
| 2        | **Declared `arguments`**    | `{{topic}}`, `{{experts}}`                                                   | The caller at dispatch; coerced to your declared type                                   |
| 3        | **Dispatch payload lookup** | `{{project_id}}`, `{{reason}}`, `{{input.<field>}}`, any `{{path.to.value}}` | The ticket/event that triggered the run                                                 |
| 4        | **Unresolved**              | —                                                                            | Renders as empty string — declare an argument with a `default` if that's not acceptable |

Variable names match `[a-zA-Z0-9_.-]+`. Scalar fields also support an inline
fallback: `{{model | default: 'claude-opus-4-7'}}`.

## The fixed slots, demystified

**`{{workflow_id}}`** — the `id:` from your own frontmatter (e.g.
`my-first-workflow`). Format: the kebab-case string you wrote. You "get" it
by writing it; Cadence echoes it back so the agent always knows which policy
file governs it.

**`{{issue_ref}}`** — the reference of the ticket/issue that triggered this
run (e.g. a Beam issue like `BEAM-42`). Comes from the dispatch event; empty
when a run isn't ticket-driven.

**`{{ticket.id}}`** — the underlying ticket identifier from the dispatch
payload.

**Where they go afterwards (analytics):** these same values are stamped on
every harness event in the session ledger (run ids, workflow id, lane slug,
usage, cost). That means the `{{workflow_id}}` you chose is your join key
across runs, costs, and evidence — pick meaningful ids.

## Declaring your own variables

Add typed `arguments` at the top level; callers supply values at dispatch,
Cadence coerces and validates:

```yaml theme={null}
arguments:
  topic:
    type: string
    required: true
  experts:
    type: int
    default: 3
agent:
  task_template: "Research {{topic}} with {{experts}} experts for {{issue_ref}}."
```

Types: `string`, `int`, `number`/`float`, `bool`/`boolean`. A missing
`required` argument **fails dispatch loudly** — it will never silently render
as empty. A declared argument always beats a same-named payload field.

## Rules of thumb

| Want                               | Do                                                        |
| ---------------------------------- | --------------------------------------------------------- |
| Pass a user choice into the prompt | Declare it in `arguments` (typed, defaulted)              |
| Reference the triggering ticket    | Use `{{issue_ref}}` / `{{ticket.id}}` — never hardcode    |
| Survive missing payload fields     | `{{field \| default: 'fallback'}}` or an argument default |
| Trace a run in the ledger          | Filter by your `workflow_id`                              |

## See also

* [Workflow Schema → arguments](/harness/workflow-schema#arguments) — exact shape
* [Snippets](/harness/snippets) — blocks these variables drop into