feat(fim): add Mercury Edit FIM support with provider-based routing

[kilo-code-bot]

Summary

Add Mercury Edit FIM model support alongside existing Codestral models. Implements provider-based routing (model name → provider) instead of a non-standard provider field. The changes include:

• Added INCEPTION_API_KEY environment variable for Inception Labs API authentication
• Removed provider field from FIM request schema; routing is now inferred from model name
• Implemented resolveFimProvider() function to map model names to providers (mistral/inception) and upstream URLs
• Updated BYOK lookup to use provider-specific keys ('codestral' for Mistral, 'inception' for Inception)
• Added BYOK-required error handling when system API key is missing
• Implemented provider-aware cost calculation: Inception uses $0.25/$0.75 pricing vs Mistral's $0.3/$0.9
• Updated Sentry span names from mistral-specific to generic 'fim-*' labels

Verification

• Modified files: src/lib/config.server.ts, src/app/api/fim/completions/route.ts, src/lib/llm-proxy-helpers.ts
• Formatting applied with oxfmt

Visual Changes

N/A

Reviewer Notes

• The inception/mercury-edit model name is normalized to mercury-edit when sent upstream to Inception API
• Mistral models retain their prefix format (mistralai/codestral-2501 → codestral-2501)
• Both Mistral and Inception APIs return OpenAI-compatible FIM responses with usage statistics
• BYOK API keys take precedence over system keys per the existing pattern
• Span names updated for consistency (e.g., fim.time_to_first_token_ms instead of mistral.time_to_first_token_ms)

[kilo-code-bot]

Code Review Summary

Status: 4 Issues Found | Recommendation: Address before merge

Overview

Severity	Count
CRITICAL	2
WARNING	2
SUGGESTION	0

Issue Details (click to expand)

Resolved since last review: the previous ProviderId / inception type mismatch on src/app/api/fim/completions/route.ts:152 remains fixed.

No new issues were found on lines that appear in the latest incremental diff (50b236c5d9b169e01e02389bbd95bba31921b263), so the findings below are carried forward from changed code outside the diff.

Fix these issues in Kilo Cloud

Other Observations (not in diff)

Issues found in unchanged code that cannot receive inline comments:

CRITICAL

File	Line	Issue
src/routers/kiloclaw-router.ts	1061	Stale running rows can be overwritten with a later run's output because controller status is matched only by user/current run state, not by the persisted run identity.
src/routers/kiloclaw-router.ts	1096	Cancel requests terminate the controller's current job without verifying it matches the requested runId, so an older stale row can cancel a newer run.

WARNING

File	Line	Issue
packages/db/src/schema.ts	3639	kiloclaw_cli_runs stores only user_id, so multi-instance users cannot disambiguate which instance a run belongs to and histories from multiple instances are merged together.
kiloclaw/src/routes/platform.ts	981	The new kilo-cli-run platform endpoints do not parse or forward instanceId, so they always target the legacy user-keyed DO instead of the selected instance.

Files Reviewed (1 file)

• src/app/api/fim/completions/route.ts

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_{Reviewed by gpt-5.4-20260305 · 324,065 tokens}

[marius-kilocode]

Is this note relevant?

[marius-kilocode]

Do we just remove it and collect now?

[chrarnoldus]

inception doesn't do collection either

[chrarnoldus]

there are real a gaps, we don't enforce the provider blocklist for example, but that's not a regression

[markijbema]

why not just make the fim provider be codestral in the first place?

[chrarnoldus]

it's called mistral everywhere, but this hack is needed for the "not all API keys support all models" feature that mistral has.