(MOT-3980) fix(shell): expose coder functions in zero-config mode

[ytallo]

Summary

Make all nine coder::* file tools available when the shell worker uses its shipped zero-config policy.

The coder resolver now uses its existing working-directory plus /tmp fallback when fs.host_roots is empty, while explicit roots continue to override that fallback. Hot reloads can also move safely between configured roots and the zero-config fallback.

Why

The default shell configuration deliberately leaves fs.host_roots empty, but startup and reload contained separate jail checks that skipped the entire coder surface. As a result, healthy harness sessions had no coder file tools even though the resolver already supported a safe fallback.

Developer experience

A fresh local stack now exposes coder tools without requiring operators to discover and configure filesystem roots first. Harness-selected workspaces remain available through the trusted per-session filesystem scope.

This does not grant parent directories automatically or weaken shell::fs::* confinement. Attempts to leave the selected workspace still require an explicit folder-access grant.

Verification

• cargo fmt --manifest-path shell/Cargo.toml -- --check
• cargo test --manifest-path shell/Cargo.toml --lib configuration::tests:: — 17 passed
• cargo test --manifest-path shell/Cargo.toml
• Live zero-config smoke: all nine coder::* functions registered after restarting only the shell worker
• Live session-scope smoke: coder::read-file read a file from the selected workspace outside the worker's static fallback roots

Fixes MOT-3980

Summary by CodeRabbit

• Bug Fixes
  • Coder functionality now remains available when shell filesystem restrictions are widened or cleared.
  • Improved fallback behavior keeps coder file resolution limited to the current directory and /tmp when no explicit base paths are configured.
  • Coder configuration now remains consistent after shell configuration reloads.

[vercel]

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[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: e36734ae-7752-43ff-8a68-049bda864dba

📥 Commits

Reviewing files that changed from the base of the PR and between dc03845 and 0ea5893.

📒 Files selected for processing (2)

• shell/src/configuration.rs
• shell/src/main.rs

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📝 Walkthrough

Walkthrough

The shell now builds and registers the coder code surface regardless of filesystem jail status. Unjailed configurations use fallback resolver roots consisting of the canonicalized current directory and /tmp, while coder base paths remain empty.

Changes

Coder surface availability

Layer / File(s)	Summary
Fallback resolver roots shell/src/configuration.rs	Unjailed configurations build coder snapshots using narrow fallback roots, with tests covering initial seeding and reload behavior.
Unconditional coder registration shell/src/main.rs	Startup always stores coder cells in AppState and registers the coder::* code surface.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Poem

A rabbit hops where coder roots grow,
Through cwd and /tmp, in a tidy row.
No jail can hide the cells away,
They register bright at break of day.
“Narrow paths!” the bunny sings,
“Let every coder surface spring!”

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/coder-zero-config-registration

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[github-actions]

skill-check — worker

0 verified, 41 skipped (no docs/).

Layer	Result
structure	✓
vale	✓
ai	✓
render	✓

Four for four. Nicely done.