fix(server)!: reject a wildcard bind with no advertised address

[chengxilo]

Which issue does this PR address?

Closes #3890

Rationale

A wildcard bind says which interfaces a node accepts on, not where a client reaches it, so publishing it as an address hands clients a target they cannot dial.

What changed?

node.advertised_address supplies it, and the server now refuses to start when server is configured with wildcard bind while leaves it unset.

Breaking:

deployments binding 0.0.0.0 without a roster must declare an address. The Helm chart can derives it from the Service DNS name and the shipped compose files name their service; anything else needs IGGY_NODE_ADVERTISED_ADDRESS. A cluster.nodes ip must now be a literal IP, and no declared address may be the unspecified one.

Some detail regarding new behavior:

When would it boot?

Standalone (cluster.enabled = false)

tcp.address	node.advertised_address	Boot	Metadata publishes
127.0.0.1:8090	unset	✅	127.0.0.1 (derived from the bind)
127.0.0.1:8090	broker.example.com	✅	broker.example.com (declared wins)
0.0.0.0:8090	unset	❌ rejected	—
0.0.0.0:8090	broker.example.com	✅	broker.example.com
any	0.0.0.0 / ::	❌ rejected	—
any	broker:8090 (carries a port)	❌ rejected	—

Cluster (cluster.enabled = true)

tcp.address only picks the bind interface here — ports come from the roster — so a wildcard is perfectly
normal.

Roster field	Value	Boot
nodes[].ip	172.28.0.101	✅
nodes[].ip	0.0.0.0 / ::	❌ rejected
nodes[].ip	iggy-server (any hostname)	❌ rejected, points at advertised_address
advertised_address	unset	✅ → publishes ip
advertised_address	broker.example.com	✅ → publishes it
advertised_address	0.0.0.0 / ::	❌ rejected
selector address	0.0.0.0 / ::	❌ rejected, error names the CIDR
node.advertised_address	set	✅ but ignored, warns at startup

Which address a client is told (advertised_for):

selector matching the client's source IP (longest prefix) → advertised_address → ip

Both modes

tcp.address	Boot
:8090 (empty host)	❌ rejected — Rust's SocketAddr has no such spelling
localhost:8090 (hostname)	❌ rejected — a literal IP is required
anything else that does not parse	❌ rejected, one message naming the fix

Edge cases

Situation	Behavior
cluster.enabled = false with [[cluster.nodes]] left behind	Roster is neither resolved nor validated —
boots even if an ip is a hostname
A selector whose CIDR does not parse	❌ rejected (previously dropped in silence)

That last row is a side fix: a malformed selector used to be swallowed, surfacing only as "clients on one network
get the catch-all address" with nothing to debug.

Local Execution

• Passed
• Pre-commit hooks ran

AI Usage

1. Claude Code (Opus)
2. Diagnosis and implementation
3. Reviewed line by line with my best effort. BUT I am not very familiar with the server side code, so I am not sure if these changes introduce any side-effect that I didn't notice. According to the changed part, I think it looks ok.
4. Yes

[github-actions]

Thanks for the PR. It is labeled S-waiting-on-review and queued for review.

Slash commands (own line, regular comment) move it around the queue:

• /ready - back to S-waiting-on-review after addressing feedback
• /author - flip to S-waiting-on-author while you finish changes
• /request-review @user-or-team - request a reviewer

See CONTRIBUTING.md for details.

[codecov]

Codecov Report

❌ Patch coverage is 92.25092% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.82%. Comparing base (ab257a0) to head (7f78459).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
core/configs/src/server_config/cluster.rs	86.04%	9 Missing and 3 partials ⚠️
core/server/src/bootstrap.rs	73.33%	2 Missing and 2 partials ⚠️
core/configs/src/server_config/validators.rs	93.75%	2 Missing and 1 partial ⚠️
core/configs/src/server_config/node.rs	97.14%	0 Missing and 1 partial ⚠️
core/server/src/http.rs	66.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master    #3923       +/-   ##
=============================================
- Coverage     83.82%   68.82%   -15.01%     
  Complexity     1358     1358               
=============================================
  Files          1212     1212               
  Lines        166148   151623    -14525     
  Branches     133622   119224    -14398     
=============================================
- Hits         139272   104352    -34920     
- Misses        23253    43712    +20459     
+ Partials       3623     3559       -64     

Components	Coverage Δ
Rust Core	67.85% <92.25%> (-16.77%)	⬇️
Java SDK	66.67% <ø> (ø)
C# SDK	40.53% <ø> (-35.55%)	⬇️
Python SDK	90.00% <ø> (ø)
PHP SDK	84.48% <ø> (ø)
Node SDK	95.94% <ø> (+0.09%)	⬆️
Go SDK	68.32% <ø> (ø)

Files with missing lines	Coverage Δ
core/configs/src/server_config/defaults.rs	100.00% <100.00%> (ø)
core/configs/src/server_config/server.rs	85.48% <ø> (ø)
core/server/src/cluster_meta.rs	99.50% <100.00%> (+0.89%)	⬆️
core/server/src/dispatch.rs	89.39% <100.00%> (-0.07%)	⬇️
core/server/src/http/error.rs	86.96% <100.00%> (+0.48%)	⬆️
core/configs/src/server_config/node.rs	97.14% <97.14%> (ø)
core/server/src/http.rs	92.73% <66.66%> (-0.38%)	⬇️
core/configs/src/server_config/validators.rs	91.94% <93.75%> (+0.18%)	⬆️
core/server/src/bootstrap.rs	80.70% <73.33%> (-0.19%)	⬇️
core/configs/src/server_config/cluster.rs	98.16% <86.04%> (-0.54%)	⬇️

... and 333 files with indirect coverage changes

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