Adds a data-driven test that loads testdata/nodeattrs_results/*.hujson
and diffs the captured SaaS-rendered netmaps against headscale's
compileNodeAttrs output. Each capture is one scenario the SaaS
control plane has rendered against the same policy headscale is asked
to compile -- the test enforces shape parity per node.
tailnet_state_caps.go enumerates the caps SaaS emits where headscale
has no equivalent concept yet (user-role admin/owner, tailnet lock,
services host, app connectors, internal magicsock and SSH tuning,
tailnet-state metadata) plus the always-on baseline (admin, ssh,
file-sharing) and the taildrive pair. stripUnmodelledTailnetStateCaps
filters both sides of cmp.Diff so the comparison focuses on the
policy-driven caps. PeerCapMap encodes which caps the Tailscale
client reads from the peer view (suggest-exit-node when exit routes
are approved, etc.) for use by the mapper.
testcapture switches to typed tailcfg/netmap/filtertype/apitype
values so schema drift between the capture tool and headscale
becomes a compile error rather than a silent test failure. Existing
compat suites (acl, grants, routes, ssh, issue_3212) move to the
typed shape.
The 53 SelfNode netmap captures and the 7 anonymizer-corrupted
suggest-charmander -> suggest-exit-node restorations in
routes_results / issue_3212 ride along.
Typed Capture/Input/Node/Topology structs for golden SaaS captures.
Schema drift between the tscap capture tool and headscale now becomes a
compile error instead of a silent test pass.
Updates #3157
