Fixes #261.

Summary

Enables the inline terminal image preview (added in #241, extended in #253) to also fire when the Codex CLI prints its Viewed Image block, which uses a tree pointer line followed by a relative path:

• Viewed Image
  └ app/docs/screenshots/issue-237/proof/pr238-proof-06-skiller-submodule-status.png

Before this change the detector only matched paths starting with /, and the API validator rejected anything that wasn't absolute, so these images were not previewed.

What changed

Frontend — packages/app/src/web/terminal-image-paths.ts

• New regex pattern anchored on the tree pointer glyphs └ and ├ and a relative path with a supported image extension.
• The two patterns (absolute path and tree-pointer + relative path) now run via a shared collector that dedupes by startIndex, so an absolute path that happens to follow a pointer is reported once.

Backend — packages/api/src/services/terminal-image-fetch-core.ts

• planTerminalImageFetch accepts an optional { baseDir } and resolves bare relative paths against it. The base dir itself must be absolute and free of traversal/control characters; the joined path is re-validated through the existing safety checks (traversal, control chars, supported extensions) before any docker exec runs.

Backend wiring — packages/api/src/services/terminal-sessions.ts

• Terminal sessions now remember the project's targetDir (e.g. /home/dev/app) and pass it as the baseDir when reading the image. This way a relative path like app/docs/... printed inside a session whose cwd is /home/dev resolves to the same file the user is looking at.

Reproduction

The new tests reproduce the issue end-to-end:

• packages/app/tests/docker-git/terminal-image-paths.test.ts
  • detects relative image paths under a tree pointer (issue 261 viewed image format)
  • detects multiple viewed images across separate lines
  • detects relative image paths under the alternative branch tree pointer
  • does not duplicate absolute paths preceded by a tree pointer
  • ignores tree pointers that do not precede an image
• packages/api/tests/terminal-image-fetch-core.test.ts
  • resolves a relative path against the provided absolute base directory
  • ignores trailing slashes on the base directory when resolving a relative path
  • still rejects relative paths when no base directory is supplied
  • rejects relative paths when the supplied base directory is not absolute
  • rejects an unsafe base directory containing traversal segments
  • rejects relative paths that contain traversal segments after resolution

Test plan

• bun run --cwd packages/api typecheck
• bun run --cwd packages/app typecheck
• bun run --cwd packages/api vitest run tests/terminal-image-fetch-core.test.ts — 17/17 pass
• bun run --cwd packages/app vitest run tests/docker-git/terminal-image-paths.test.ts — 18/18 pass
• bun run --cwd packages/app vitest run — 274/274 pass
• bun run --cwd packages/api vitest run — 90/91 pass (one pre-existing failure in tests/projects.test.ts requires a local Docker daemon and is unrelated to this change)

Safety

The path that is finally handed to docker exec is still subject to all of the previously existing checks:

• must be absolute after resolution
• no whitespace or control characters
• no . / .. segments (raw or percent-encoded)
• supported extension only (png, jpg, jpeg, gif, webp)
• 10 MB cap

Additional checks introduced here:

• when baseDir is supplied it must itself be absolute and free of traversal/control characters
• relative paths without a baseDir continue to fail with the same message as before