Tag↔group PascalCase collision causes unnecessary '2' suffixes on sub-clients

[HavenDV]

Problem

When an OpenAPI spec has both tags and x-fern-sdk-group-name extensions that resolve to the same PascalCase name, AutoSDK adds 2 suffixes to sub-client class names to resolve the "collision" — even though the original tag ends up with zero assigned methods and should be filtered out.

Example: Vectara SDK

The Vectara spec has:

• OpenAPI tag: "Corpora"
• x-fern-sdk-group-name: corpora on all operations tagged with "Corpora"

With UseExtensionNaming=true (default), AutoSDK:

1. Collects all OpenAPI tags → ["Corpora", "Encoders", "Rerankers", ...]
2. Scans x-fern-sdk-group-name values → adds ["corpora", "encoders", "rerankers", ...] as ad-hoc tags
3. Both "Corpora" and "corpora" resolve to PascalCase Corpora → collision detected → suffix 2 added
4. Operations are reassigned from tag "Corpora" to group "corpora" → tag "Corpora" ends up empty
5. Empty tags are filtered out — but the collision was already resolved with the 2 suffix

Result: Corpora2Client, Encoders2Client, Rerankers2Client, Agents2Client, etc.

Expected Behavior

AutoSDK should resolve naming collisions after filtering out empty tags (tags that lost all their operations to x-fern-sdk-group-name reassignment). Since the original tag "Corpora" has zero methods after reassignment, it should be removed before collision detection runs, and the group "corpora" should produce a clean CorporaClient.

Current Workaround

Strip x-fern-sdk-group-name and x-fern-sdk-method-name from the spec in generate.sh:

python3 -c "
import re, sys
with open('openapi.yaml') as f:
    lines = f.readlines()
out = []
for line in lines:
    stripped = line.strip()
    if stripped.startswith('x-fern-sdk-group-name:') or stripped.startswith('x-fern-sdk-method-name:'):
        continue
    out.append(line)
with open('openapi.yaml', 'w') as f:
    f.writelines(out)
"

Note: This is fragile — it doesn't handle YAML list-style values like:

x-fern-sdk-group-name:
- auth

A proper YAML parser (PyYAML) is needed for robust stripping.

Affected SDKs

Any SDK whose spec uses Fern-generated x-fern-sdk-group-name values that match the OpenAPI tag names in PascalCase. Currently known: Vectara.

Suggested Fix

In Data.cs, move the collision resolution step to after the empty-tag filtering step. The flow should be:

1. Collect tags + ad-hoc groups
2. Reassign operations based on x-fern-sdk-group-name
3. Filter out empty tags (tags with zero assigned methods)
4. Then resolve PascalCase naming collisions among remaining tags/groups

[HavenDV]

Fixed on current main in 864faaf. Tag/group names are now resolved in two phases: operations are assigned provisional raw tag/group names first, then empty tags are dropped, and only the surviving tags participate in final collision resolution. This avoids spurious suffixes like when steals all methods from the original OpenAPI tag. Added focused unit and CLI/build regressions, and the Publish workflow passed: https://github.com/tryAGI/AutoSDK/actions/runs/23702049969