feat(topograph): support trimming upper network tiers

[dmitsh]

No description provided.

[greptile-apps]

Greptile Summary

This PR adds support for trimming upper network tiers (spine and/or core switch levels) from the three-tier topology graph, configurable via a new trimTiers parameter (valid range 0–2). The feature is wired end-to-end across all providers (AWS, GCP, LambdaI, Nebius, OCI API, OCI IMDS), the gRPC forwarding path, and simulation loaders, and is backed by a new integration test and thorough unit tests.

All previously raised review concerns have been addressed in this revision:

• trimmedTiers now returns a local slice copy — no mutation of the original InstanceTopology.
• GetTrimTiers correctly handles both int (YAML) and float64 (JSON) values, and rejects values outside [0, 2].
• grpc_client.go now reads trimTiers from the request params instead of hardcoding 0.
• All providers (including the previously missing Nebius path) are fully wired.

Remaining concern:

• All LoaderSim functions read trimTiers from SimulationParams.TrimTiers (decoded via mapstructure), bypassing the 0–2 range validation that GetTrimTiers enforces for real providers. A simulation request with "trimTiers": 3 is silently accepted and trims all three tiers, while the same value is rejected for real providers.

Confidence Score: 4/5

• Safe to merge with one minor inconsistency in simulation provider validation.
• All previously flagged issues are resolved. The only remaining issue is that simulation providers accept out-of-range trimTiers values (> 2) without error because they use mapstructure decoding rather than GetTrimTiers. This only affects simulation paths and does not impact production providers.
• pkg/providers/providers_sim.go and all *_sim.go provider files — LoaderSim implementations do not call GetTrimTiers and therefore skip range validation.

Important Files Changed

Filename	Overview
pkg/topology/graph.go	Adds trimTiers int parameter to ToThreeTierGraph and introduces the trimmedTiers helper that returns a local copy of the tier IDs with upper levels zeroed — no mutation of the original InstanceTopology.
pkg/providers/providers.go	Refactors StringFromMap into a generic FromMap[T], adds GetTrimTiers with proper float64 coercion (for JSON-decoded params) and a 0–2 range guard. Error messages corrected to "must be of type %T".
pkg/providers/providers_sim.go	Adds TrimTiers int to SimulationParams; however all LoaderSim functions use p.TrimTiers directly (via mapstructure) rather than calling GetTrimTiers, bypassing the 0–2 range validation enforced for real providers.
pkg/providers/nebius/provider.go	Previously flagged as missing trimTiers support — now fully wired: reads GetTrimTiers, stores in baseProvider, and passes to ToThreeTierGraph.
pkg/server/grpc_client.go	Previously flagged hardcoded 0 replaced: now calls GetTrimTiers(tr.Provider.Params) and passes the result to ToThreeTierGraph, keeping the forwarded gRPC path consistent with the local path.
pkg/server/http_server_test.go	Adds an integration test (Case 7) for trimmed tree topology via gcp-sim. Minor mixed tab/space indentation on line 102 of the slurmTrimmedTreePayload constant.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[HTTP/gRPC Request\nwith trimTiers param] --> B{Provider type?}
    B -- Real provider --> C[Loader\nGetTrimTiers validates 0-2\nstores in baseProvider.trimTiers]
    B -- Sim provider --> D[LoaderSim\nGetSimulationParams via mapstructure\np.TrimTiers - no range check]
    C --> E[GenerateTopologyConfig]
    D --> E
    E --> F[ClusterTopology.ToThreeTierGraph\nprovider, cis, trimTiers, normalize]
    F --> G[trimmedTiers helper\nreturns local copy of tier IDs\nzeros out top N entries]
    G --> H{swID empty?}
    H -- yes --> I[skip - tier trimmed from graph]
    H -- no --> J[add switch vertex to tree]
    J --> K[Return Vertex tree\nwithout trimmed upper tiers]
    I --> K

Loading

Comments Outside Diff (2)

1. pkg/providers/providers_sim.go, line 31 (link)

   Simulation providers bypass GetTrimTiers validation

   All LoaderSim functions extract trimTiers from p.TrimTiers (populated via GetSimulationParams → mapstructure), completely bypassing the 0–2 range validation that GetTrimTiers enforces for every real provider. A simulation request with "trimTiers": 3 will succeed — trimmedTiers will happily zero out all three switch levels — while the identical value is rejected for real providers.

   For example, in pkg/providers/gcp/provider_sim.go:

   p, err := providers.GetSimulationParams(cfg.Params)
   ...
   return NewSim(clientFactory, p.TrimTiers), nil  // no range check

   Consider calling GetTrimTiers inside LoaderSim (same as real providers) and using its validated result instead of the raw p.TrimTiers:

   trimTiers, err := providers.GetTrimTiers(cfg.Params)
   if err != nil {
       return nil, httperr.NewError(http.StatusBadRequest, "parameters error: "+err.Error())
   }
   return NewSim(clientFactory, trimTiers), nil

   The same inconsistency exists in the LoaderSim of every provider that was updated in this PR (aws, gcp, lambdai, nebius, oci).

2. pkg/server/http_server_test.go, line 102 (link)

   Mixed tab/space indentation in JSON string literal

   Line 102 uses a hard tab character (\t) for indentation while every other line in slurmTrimmedTreePayload uses spaces. JSON is whitespace-agnostic so this won't affect parsing, but it creates an inconsistency visible in editors and diffs.

   _{Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!}

_{Last reviewed commit: 4e20a43}

[codecov]

Codecov Report

❌ Patch coverage is 63.41463% with 45 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.96%. Comparing base (a9b6076) to head (4e20a43).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/providers/aws/provider.go	8.33%	11 Missing ⚠️
pkg/providers/gcp/provider.go	10.00%	9 Missing ⚠️
pkg/providers/nebius/provider.go	10.00%	9 Missing ⚠️
pkg/providers/oci/provider_api.go	11.11%	8 Missing ⚠️
pkg/providers/oci/provider_imds.go	0.00%	6 Missing ⚠️
pkg/server/grpc_client.go	50.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #233      +/-   ##
==========================================
- Coverage   66.99%   66.96%   -0.04%     
==========================================
  Files          82       82              
  Lines        4572     4646      +74     
==========================================
+ Hits         3063     3111      +48     
- Misses       1398     1424      +26     
  Partials      111      111              

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[ravisoundar]

lgtm