#8660: fix: respect agents.defaults.models.*.params.maxTokens in image tool

## Summary - Image tool was using hardcoded `maxTokens: 512`, ignoring model-specific config - This caused models with thinking/reasoning to exhaust tokens before producing output - Result: "Image model returned no text" errors ## Changes - Added `resolveImageMaxTokens()` helper to read `agents.defaults.models[modelKey].params.maxTokens` - Falls back to 512 for backwards compatibility when not configured ## Configuration Example ```json { "agents": { "defaults": { "models": { "openrouter/google/gemini-3-pro-preview": { "params": { "maxTokens": 8192 } } } } } } ``` ## Test plan - [x] Run type checking (`npm run check`) - [x] Run image tool tests (`vitest run src/agents/tools/image-tool`) Fixes #8096 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- greptile_comment --> <h2>Greptile Overview</h2> <h3>Greptile Summary</h3> This PR removes the hardcoded `maxTokens: 512` in the image tool and instead resolves `maxTokens` from `agents.defaults.models["<provider>/<modelId>"].params.maxTokens`, falling back to 512 when not configured. This aligns image tool completion limits with per-model configuration so reasoning/thinking-enabled models don’t exhaust the output budget before producing text. The change is localized to `src/agents/tools/image-tool.ts` and only affects the `complete(...)` call for non-MiniMax providers; MiniMax continues using its dedicated `minimaxUnderstandImage` path. <h3>Confidence Score: 4/5</h3> - This PR is likely safe to merge and should fix the hardcoded token limit, with a small risk of config-key mismatches preventing the override from applying in some cases. - The change is small and well-scoped (one helper and one call site). Main uncertainty is whether `${provider}/${modelId}` matches the canonical key format used in `agents.defaults.models` across all registries/providers, which could cause silent fallback to the default. - src/agents/tools/image-tool.ts (verify model key normalization matches config expectations) <!-- greptile_other_comments_section --> <!-- /greptile_comment -->