fix(agent-core-v2): fall back to the configured default model for image format gating

[RealKai42]

Related Issue

Follow-up to #3649 (no tracking issue; gap found during end-to-end smoke testing of that PR).

Problem

#3649 made image format acceptance provider-aware, but every gate resolved the provider type only from the bound model. A fresh session that has not explicitly bound a model yet (no per-request model, no agent_config selection) has an empty profile alias, so getModelProviderType() returned undefined and every gate fell back to the baseline PNG/JPEG/GIF/WebP set. Two supported flows hit this:

• A first prompt with a HEIC/HEIF/BMP attachment on a session whose default_model is served by Kimi: the image was persisted as an attachment and replaced by a text notice even though the turn's effective model is the Kimi default.
• A first prompt that selects a profile without naming a model: bind() falls back to the configured default_model, but the kap-server route runs media resolution before the bind, so the gate saw undefined again.

What changed

IAgentProfileService.getModelProviderType(alias?) now resolves alias ?? boundModelAlias ?? config defaultModel before consulting the catalog, mirroring the fallback bind() itself applies. One change covers every consumer (prompt-entry gate, kap-server prompt/skill routes, MCP tool results). Explicit alias and bound-model resolution are unchanged; when neither a bound model nor a resolvable default exists, the method still returns undefined and gates keep the baseline set.

Tests (red-first): profile-level fallback including precedence and non-Kimi/missing defaults (profileOps.test.ts); kap-server route regressions for both flows above (prompts.test.ts). Verified with the full agent-core-v2 / kap-server / acp-server / klient suites plus a live end-to-end smoke (real server process, mock OpenAI-compatible provider, sips-generated HEIC/BMP files): 20/20 checks pass, including the previously failing unbound-first-prompt case.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue (external PRs: the issue must have a maintainer's /approve).
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

[changeset-bot]

🦋 Changeset detected

Latest commit: 13a99fd

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@moonshot-ai/kimi-code	Patch

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-08T12:15:59.702798Z	13a99fd	PR opened
🔒 Security Review	✅ Completed 2026-09-08T12:16:07.579458Z	13a99fd	PR opened

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commit: 13a99fd