feat(config): per-project [projects.display] override

[Cigarrr]

Summary

Allow each [[projects]] entry to override individual fields of the global [display] block, on a per-field basis. Useful when you want one project to run quiet while others stay verbose, or vice versa, without splitting into separate cc-connect instances.

Schema

[display]
thinking_messages = true
tool_messages = true

[[projects]]
name = "noisy-project"
[projects.display]
thinking_messages = false  # overrides only this field
tool_messages = false

Each sub-field is independently optional; unset fields fall back to the global [display] value, then to the built-in default.

Resolution order (per field)

1. [projects.display].<field> — highest precedence
2. [display].<field>
3. built-in default

All four DisplayConfig fields participate (ThinkingMessages, ToolMessages, ThinkingMaxLen, ToolMaxLen).

Backward compatibility

• Projects with no [projects.display] block see no behavior change.
• Legacy quiet (root or per-project) is preserved: if quiet is in effect AND neither layer set thinking_messages / tool_messages, they default to false — same as before, just extended to honor project-level overrides when present.

Tests

7 new sub-tests in TestEffectiveDisplay_ProjectOverride cover:

• project overrides global thinking_messages
• project unset falls back to global
• both unset falls back to default
• project overrides max-len fields
• project quiet still respected when project display unset
• project display.thinking_messages true overrides project quiet
• nil project display behaves like before

go test ./... passes (the 4 pre-existing failures on main — TestProcessInteractiveEvents_AppendsReplyFooterWhenEnabled, TestProcessInteractiveEvents_ReplyFooterPrefersSessionRuntimeState, TestResolveLocalDirPath_AcceptsSubdir, TestGetModelAndReasoningEffort_FromRuntimeConfigWhenUnset — are unrelated to this change).

Docs

config.example.toml updated with a commented-out [projects.display] example next to the global [display] section.

[chenhg5]

Review Summary

Clean implementation of per-project [projects.display] override. The per-field resolution logic is well-designed and backward-compatible.

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✅ Good:

1. Per-field resolution: pickBool / pickInt helpers cleanly implement the precedence: project → global → default.

2. Legacy quiet preserved: When quiet=true AND neither layer explicitly sets thinking_messages / tool_messages, they default to false. Project-level [projects.display] takes precedence over both global display and quiet.

3. Comprehensive tests: 7 test cases in TestEffectiveDisplay_ProjectOverride cover all resolution paths.

4. Documentation: Clear config example showing the per-field override pattern.

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LGTM. CI green.