#3582 dns_records lookup: distinguish no-match from API/auth/network failure (or add a list method)

Problem

dns_records lookup throws No dns records found matching filters: ... when nothing matches. It also throws (from listAll) on auth failures, network errors, and API errors. A caller (a workflow step, or another model via context.runModel()) only sees a failed method in both cases, so it cannot tell "the record does not exist yet" from "the lookup could not run".

This matters for idempotent create-or-adopt flows: the natural pattern is "lookup; if absent, create". Today that pattern either has to treat every lookup failure as absence (and then try to create a record while, say, the token is wrong), or parse the error message text.

There is also no list method on the model, so there is no non-throwing way to ask "which records match?".

Proposed solution

Either of these would solve it:

• Give lookup an opt-in such as allowMissing: true (argument) that writes nothing and returns successfully with zero data handles (or writes a small lookupResult resource with found: false) when there are no matches, while still throwing on API/auth/network errors and on multiple matches.
• Or add a list method that applies the same filters and writes the matches (possibly zero) as resources or a single list resource, succeeding with an empty result when nothing matches.

Alternatives

Matching on the error message text works but is brittle. Calling get by id requires already knowing the id.

Upstream repository: https://github.com/swamp-club/swamp-extensions

Environment

• Extension: @swamp/cloudflare/dns@2026.10.17.1
• swamp: 20261013.025835.0-sha.1b6f0c59
• OS: linux (aarch64)
• Deno: 2.9.7
• Shell: /usr/bin/zsh