Implement OSPF control plane and dynamic routing

[jojo-swe]

Scope

This is a real simulator feature, not a documentation-only change.

• adds OSPF configuration types to the shared model
• builds full adjacencies from active links, matching subnets and area configuration
• originates deterministic router LSAs and a shared LSDB
• runs Dijkstra SPF with interface costs and deterministic tie-breaking
• installs OSPF routes with next hop, outgoing interface, metric and advertising router
• integrates learned routes into forwarding with administrative-distance ordering
• recomputes topology on demand so link deletion withdraws routes immediately
• exposes OSPF snapshots through the World API
• adds regression coverage for adjacency, LSDB, SPF, bidirectional forwarding, route withdrawal and area mismatch

Validation status

The branch has been submitted to GitHub Actions. I am not claiming it passes until the workflow result has been inspected.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 29cdbf92-fa0d-4185-b2c7-e9431108fe44

📥 Commits

Reviewing files that changed from the base of the PR and between 52405e7 and 15ce6d7.

📒 Files selected for processing (5)

• apps/api/src/regression/ospf.test.ts
• apps/api/src/sim/ospf.ts
• apps/api/src/sim/routing.ts
• apps/api/src/sim/world.ts
• packages/shared/src/types.ts

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch agent/ospf-control-plane

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[devin-ai-integration]

Devin Review found 1 potential issue.

View 1 additional finding in Devin Review.

[devin-ai-integration]

🟡 Automatically chosen router identifier picks the wrong address

The router identifier is derived by sorting interface addresses as plain text (.sort() at apps/api/src/sim/ospf.ts:95) and taking the last one, instead of the numerically highest address, so a router without an explicitly configured identifier can advertise itself under the wrong identity.

Impact: When no router-id is configured, a device may present a router identity that does not match real-device behavior (highest IP), and tie-breaking/ordering can differ from expectations, hurting fidelity and reproducibility.

Why lexicographic sort mis-orders IPv4 addresses

stableRouterId (apps/api/src/sim/ospf.ts:88-97) collects ipv4Address values and calls .sort() (default string comparison) then .at(-1). String order treats each octet character-by-character, so e.g. ["192.168.1.20", "192.168.1.3"] sorts to ["192.168.1.20", "192.168.1.3"] and returns 192.168.1.3, whereas OSPF selects the numerically highest (192.168.1.20). This only triggers when config.ospf.routerId is undefined (allowed by configureOspf at apps/api/src/sim/world.ts:174). CONTRIBUTING.md's "Fidelity Over Convenience" and determinism rules make correct highest-IP selection the expected behavior.

Prompt for agents

In stableRouterId (apps/api/src/sim/ospf.ts:88-97), the fallback router-id selection sorts interface IPv4 addresses lexicographically with .sort() and takes the last element. This does not select the numerically highest IPv4 address the way OSPF does (e.g. 192.168.1.20 should beat 192.168.1.3, but string sort picks 192.168.1.3). Convert each address to its integer form (ipv4ToInt is available in @netsim/shared) and pick the address with the maximum integer value, so the auto-derived router identifier matches real-device behavior and stays deterministic.

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