Restore Cohere compatibility defaults

[Promansis]

Linked issue

Closes Pasta-Devs#2387

Why this change

• Cohere connections created from the provider picker were seeded with refactor-only v2 defaults instead of the legacy OpenAI-compatible Cohere endpoint.
• The provider catalog is the source for create-time connection defaults, so the catalog drift caused new Cohere connections to inherit the wrong base URL and model endpoint.

What changed

• Restored Cohere's defaultBaseUrl to https://api.cohere.ai/compatibility/v1.
• Restored Cohere's modelsEndpoint to /models.

Refactor impact

Primary owner:

React-free engine provider contracts.

Impact areas reviewed:

• CreateConnectionModal seeds new connections from PROVIDERS[provider].defaultBaseUrl.
• ConnectionEditor displays and reseeds provider defaults from the same provider catalog.

Boundary notes:

• Change stays inside src/engine/contracts/constants/providers.ts.
• No shared API, Tauri, Rust, remote-runtime, or feature-layer boundary changes.

Pressure points touched:

• None.

Validation

• Matching validation command passes locally (for example pnpm typecheck, pnpm build, pnpm check:architecture, pnpm check:docs, or full pnpm check when warranted)
• Full pnpm check passes before PR push/handoff
• Human/manual validation completed by contributor or reviewer

Manual verification notes

• pnpm typecheck
• pnpm check
• Static trace confirmed create-time seeding reads PROVIDERS[provider].defaultBaseUrl.
• Live Cohere provider transport was not exercised.

Feature Discoverability

Check exactly one:

• Updated src/features/shell/discovery/ because this PR adds or materially changes a user-discoverable feature, workflow, setting, mode, panel, import path, agent, media capability, or advanced tool.
• N/A because this PR is only a bugfix, refactor, test, docs, internal wiring, visual polish, copy edit, or compatibility fix and does not add a new thing users need to find.

Reason:

• Provider default compatibility fix only; no new user-discoverable feature.

Docs and release impact

• No docs changes needed
• Updated README.md
• Updated CONTRIBUTING.md
• Updated docs/developer/
• Updated repo skills or AGENTS.md
• Confirmed this PR does not restore old staging/package-workspace/release claims

UI evidence

• Not applicable; no visible UI layout or interaction change.

[github-actions]

✅ Bunny Review Completed

Tip

Review posted. The specimen has left the observation table.

• Commit: c40462d - Restore Cohere compatibility defaults

[github-actions]

🐰 Bunny Review

Bunny Merge Signal: Ready With Notes

Warning

READY WITH NOTES
No actionable defects were isolated, but non-blocking notes remain.

Findings	Nitpicks	Controls	Reviewed Head	Mode
0	0	1 warn, 1 pass	c40462de	full

Note

Mode: full
Head: c40462d - Restore Cohere compatibility defaults
Base: origin/refactor - Merge remote-tracking branch 'origin/refactor' into bunny-ci-review-hardening

🧭 Specimen Summary

• The specimen confines its experiment to one provider contract: Cohere abandons the old mismatched v2 base plus /v1/models suffix and adopts the OpenAI-compatible compatibility surface with a plain /models endpoint. A small incision, certainly, but provider URL arithmetic is the sort of delicate apparatus that determines whether model discovery breathes or merely returns a decorative failure.

🔎 Isolated Defects

Tip

No actionable defects isolated.

🧹 Nitpicks

• None recorded.

✅ Control Checks

Status	Type	Check	Detail
✅ PASS	CI Timing	CI Status	Expected CI controls completed without a reported failure.
⚠️ WARN	Proof Gap	Cohere provider smoke	No focused Cohere model-listing smoke result appears in the packet, so https://api.cohere.ai/compatibility/v1/models is coherent by inspection rather than demonstrated through Marinara's existing Authorization-header transport.

🧪 Observations

• Inspected the full diff from merge base 332fbef to head c40462d; only src/engine/contracts/constants/providers.ts changed.
• Checked AGENTS.md and the architecture guard: the change stays in the React-free engine contract layer and introduces no feature, Tauri, Zustand, or shared API adapter imports.
• Reviewed changed identifier usage for defaultBaseUrl, modelsEndpoint, and cohere; visible consumers seed connection UI state and model-list metadata from this definition rather than embedding a competing Cohere path.

🧰 CI Status

• pass: Frontend, Architecture, and Organization
• pass: Rust Capability Layer
• pass: Browser Smoke and Performance
• note: Bunny gates only required job conclusions from ci-checks.json; advisory reports such as continue-on-error dependency checks are not included in this status.