Add custom project icons with an in-app image picker

[guivieiras]

Projects can use custom images through the project menu or command palette. The picker browses the attached host and keeps a normalized copy there, so removing the original does not break a manual icon. Use project default clears the choice and refreshes every connected client, including an already selected default.

Defaults come from iconPath in the project-root tcode.json, or t3.json only when the primary file is absent. Project configuration documents file selection, host-relative and absolute paths, unknown fields, invalid JSON/types, image limits, overrides and refresh behavior. The dedicated configuration reader owns these rules. The document also records requirements for a future preserving, atomic editor; configuration writing is not added here.

The host owns thumbnail and display-size raster generation in one implementation. Source pixel limits bound the floating-point resize allocation in addition to decoder limits. Clients return complete host paths unchanged, so a client OS cannot introduce its own separators into a remote path. Icon cache entries refresh after reconnect and reset, and the picker exposes selection to accessibility clients. Icons appear across project views; compact thread status indicators take precedence.

Tests retain the existing persistence/copy/replacement/reset, old-index compatibility and Enter-key regression coverage. The two transparent-edge tests are consolidated at the shared host raster owner. Added cases protect foreign host paths, cached successes/errors across reconnect/reset, resource rejection, map-only configuration and cleanup only after successful index persistence (without deleting external files). UI fixtures use asynchronous protocol replies, keeping file validation at the host owner and exercising the same image-loading path as production. This removes the browse-query synchronous branch and the Windows file-handle cleanup race from the former live-host cache fixture. The existing live-host sidebar/shell fixtures still need a test-only image-query scheduling adapter; the new icon fixtures exercise the asynchronous path. The cache regression establishes an initial Index baseline before reconnecting, and also fails when reconnect baseline clearing is temporarily removed.

Thread lists with matching sample data before and after.

Desktop · Ungrouped

Before	After

Desktop · Grouped

Before	After

Mobile · Ungrouped

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Mobile · Grouped

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Change icon from the command palette

Change project icon from the project menu

Choose an image in the in-app file picker

Validation

Passed on macOS in an isolated worktree and build directory:

• cargo fmt --all --check
• cargo clippy --workspace --all-targets --locked -- -D warnings
• cargo build --workspace --locked
• cargo test --workspace --locked
• cargo-machete . (CI version 0.9.2)
• RUSTFLAGS='-D warnings' IPHONEOS_DEPLOYMENT_TARGET=26.0 cargo check -p tcode-ios --target aarch64-apple-ios-sim --locked
• RUSTFLAGS='-D warnings' cargo check -p tcode-web --target wasm32-unknown-unknown --locked
• RUSTFLAGS='-D warnings' CARGO_NDK_PLATFORM=26 cargo ndk -t arm64-v8a check -p tcode-android --locked (NDK 27.1.12297006)

Temporarily removing the fixes made four regressions fail: oversized image conversion, positional-array config, foreign host paths and cached icon recovery. Restoring the final source made them pass. The existing transparent-edge regression now covers thumbnail and display sizes through the same host implementation.

Manual validation used a disposable profile: light/dark, wide/compact windows, command-palette entry, directory navigation, path Enter without dismissal, filtering, scrolling, focus outlines, selecting/saving and resetting. Reset removed the managed PNG and cleared the persisted override. The screenshots above illustrate the feature; the refactor retains its layout.

An initial shared-cache run hit the existing terminal burst throughput threshold; the complete isolated rerun passed. That independently reproduced runtime issue is fixed separately in #448. The macOS debug link emitted an unwind-table size warning, and Cargo reports the existing block dependency future-compatibility notice. Native Windows/Linux execution remains for CI; mobile/Web checks above are compilation checks.

[Tryanks]

Hey @guivieiras, thanks — I've decided to take this feature.

This PR introduces a new project-level config file, tcode.json. I'd like a doc that records everything about it (something like docs/project-config.md): where it lives, the iconPath field, how relative paths resolve, the t3.json fallback, and how unknown fields and bad JSON are handled. I'd also like Tcode to be able to manage or generate tcode.json down the line.

Once all of these PRs are merged I plan to tackle #409 and then cut a new release.

[guivieiras]

@Tryanks nice, thanks!