Bug: /model search steals literal s and ranks loose matches first

[dennisonbertram]

Summary
The /model picker search/autocomplete path behaved poorly for DeepSeek-style queries. Typing deeps could not enter the literal s because s was treated as the star shortcut during search. Typing d could show Anthropic/Claude results ahead of DeepSeek because search only matched display-name substrings.

Impact
Model search feels broken and unpredictable: provider prefixes like d or deep do not reliably surface DeepSeek first, and users cannot type normal queries containing s.

Steps to reproduce

1. Open the TUI and run /model.
2. Type d.
3. Observe Claude/Anthropic-style results can appear before DeepSeek.
4. Continue typing deeps.
5. Observe s is consumed by the star shortcut instead of being added to the filter.

Expected vs actual behavior
Expected: printable characters typed during search are appended to the search query, and provider/model prefix matches rank above loose substring matches.
Actual: s toggles a star while search is active, and loose display-name substring matches can rank first.

Suspected root cause
The TUI key handler treated s as star whenever search was active, and model search filtered only by display name in catalog order without relevance ranking.

Proposed fix direction
Limit the s star shortcut to provider model browsing when no search query is active. Search across provider label, provider key, display name, and model ID, ranking exact/prefix matches ahead of word/substring matches.

Test plan / regression coverage
Add component tests for DeepSeek provider/model-id ranking and a root TUI regression proving deeps remains a literal query and resolves to DeepSeek.

Related docs/log entries
See docs/logs/engineering-log.md and docs/logs/long-term-thinking-log.md entries dated 2026-04-30.

[dennisonbertram]

🤖 deep-claude starting — deep-claude/issue-573-bug---model-search-steals-literal-s-and-ranks-loos

[dennisonbertram]

Fix implemented and PR created at #640.

Changes

• Bug 1 (s steals literal): Star toggle now only fires at BrowseLevel==1 with no active search. During search, "s" is treated as a literal character.
• Bug 2 (ranking): visibleModels() now searches across DisplayName, ProviderLabel, Provider key, and model ID. Results are ranked: prefix matches first, then substring matches, with starred models first within each tier.
• filteredProviders(): Also expanded to match on ProviderID in addition to Label.

Files changed

• cmd/harnesscli/tui/model.go
• cmd/harnesscli/tui/components/modelswitcher/model.go

See the PR for full details.