fix: diagnose repeated restricted downloads

[mannie-exe]

Summary

• surface rerun restricted entries when build --continue still fails
• stop trusting unchanged preexisting restricted cache files for new pending sessions with a baseline
• add regressions for stale-cache refresh, rerun diagnostics, and continue recovery

Test plan

• cargo fmt --all
• cargo test -q -p empack-lib --features test-utils restricted_build -- --nocapture
• cargo test -q -p empack-lib --features test-utils commands -- --nocapture
• cargo test -q -p empack-tests --test build_continue -- --nocapture
• cargo test -q -p empack-lib --features test-utils parse_export_restricted_output_preserves_deceasedcraft_section_sign_filename -- --nocapture
• git diff --check

[greptile-apps]

Greptile Summary

This PR improves the build --continue failure path by surfacing which restricted downloads are still required after a continue attempt, displaying a stale-cache diagnostic when the same entries recur, and stopping the cache from trusting preexisting unchanged files when a candidate_baseline is present. New unit and integration tests cover the stale-cache refresh, rerun diagnostic, and continue-recovery flows.

Confidence Score: 5/5

Safe to merge; the one finding is dead code that doesn't affect runtime behavior.

All identified issues are P2 or lower. The unreachable fallback error path in commands.rs is cosmetic dead code — the correct, more-informative error is always returned. Core stale-cache logic and comparison helpers are well-tested.

crates/empack-lib/src/application/commands.rs (dead fallback branch lines 3623–3626)

Important Files Changed

Filename	Overview
crates/empack-lib/src/application/commands.rs	Adds rerun diagnostics and detailed entry surfacing to continue-build failure path; one unreachable fallback error branch is dead code.
crates/empack-lib/src/empack/restricted_build.rs	Introduces CacheEntryStatus enum and cache_entry_status helper; correctly treats preexisting-unchanged cache files as stale when a baseline is present.
crates/empack-lib/src/application/commands.test.rs	Adds stale-cache refresh, rerun-diagnostic, and continue-recovery unit tests; negative assertions on diagnostic text are trivially satisfied since warnings go through the status display channel, not the error.
crates/empack-lib/src/empack/restricted_build.test.rs	Adds comprehensive unit tests for missing_cached_entries, stage_cached_entries_to_destinations, and import_matching_downloads_into_cache under the new stale-cache logic; covers exact, fallback, and legacy paths.
crates/empack-tests/tests/build_continue.rs	Adds an end-to-end integration test verifying that a stale restricted cache entry is refreshed from a new exact manual download and that the continued build succeeds.

Prompt To Fix All With AI

This is a comment left during a code review.
Path: crates/empack-lib/src/application/commands.rs
Line: 3616-3626

Comment:
**Unreachable fallback error path**

`restricted_rerun_error_detail` only returns `None` when its input slice is empty — but this code runs inside `if !restricted_entries.is_empty()`, so `dedup_restricted_mod_infos` always yields at least one entry and the function always returns `Some(...)`. The fallback `return Err` on line 3623 is dead code: the less-informative message can never be emitted.

Alternatively, replace `restricted_rerun_error_detail` with a non-`Option`-returning helper to make the invariant explicit.

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (3): Last reviewed commit: "fix: trim duplicate rerun diagnostics" | Re-trigger Greptile}

[codecov]

Codecov Report

❌ Patch coverage is 96.51347% with 22 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
crates/empack-lib/src/empack/restricted_build.rs	74.54%	14 Missing ⚠️
crates/empack-lib/src/application/commands.rs	94.52%	8 Missing ⚠️

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