docs(05-02): complete shell decoder cross-validation tests plan

- SUMMARY.md: 6/6 tests pass (single, multi, no-compress, empty, large, Cyrillic)
- STATE.md: Phase 5 complete, 8 plans total, 80% progress
- ROADMAP.md: Phase 5 marked complete (2/2 plans)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.planning/phases/05-shell-decoder/05-02-SUMMARY.md

@@ -0,0 +1,105 @@
+---
+phase: 05-shell-decoder
+plan: 02
+subsystem: shell-decoder
+tags: [posix-sh, cross-validation, sha256, test-script, busybox, cyrillic]
+
+# Dependency graph
+requires:
+  - phase: 05-shell-decoder
+    plan: 01
+    provides: "shell/decode.sh -- busybox-compatible POSIX shell decoder"
+  - phase: 02-core-archiver
+    provides: "Rust archiver CLI for creating test archives"
+provides:
+  - "shell/test_decoder.sh -- cross-validation test script (6 tests, Rust pack -> Shell decode -> SHA-256 verify)"
+  - "Validated shell decoder correctness across all edge cases: text, binary, no-compress, empty, large, Cyrillic filenames"
+affects: [06-obfuscation]
+
+# Tech tracking
+tech-stack:
+  added: [bash-test-framework]
+  patterns: [cross-validation-testing, rust-pack-shell-decode-sha256-verify]
+
+key-files:
+  created:
+    - shell/test_decoder.sh
+
+key-decisions:
+  - "All 6 tests passed on first run -- no decode.sh fixes needed"
+  - "Used sh (not bash) to invoke decode.sh in tests for POSIX compatibility validation"
+  - "Followed kotlin/test_decoder.sh pattern for consistency across decoder test suites"
+
+patterns-established:
+  - "Cross-validation test pattern: Rust pack -> decoder unpack -> SHA-256 comparison (reusable for any decoder)"
+  - "Test script structure: prerequisites -> build -> test cases -> summary with pass/fail counts"
+
+requirements-completed: [SHL-01, SHL-02, SHL-03]
+
+# Metrics
+duration: 2min
+completed: 2026-02-25
+---
+
+# Phase 5 Plan 2: Shell Decoder Cross-Validation Tests Summary
+
+**Cross-validation test script with 6 test cases (single file, multiple files, no-compress, empty, large 100KB, Cyrillic filename) all passing on first run via Rust pack -> sh decode.sh -> SHA-256 verify**
+
+## Performance
+
+- **Duration:** 2 min
+- **Started:** 2026-02-24T22:42:47Z
+- **Completed:** 2026-02-24T22:44:38Z
+- **Tasks:** 2
+- **Files created:** 1
+
+## Accomplishments
+- Created comprehensive cross-validation test script (275 lines) following kotlin/test_decoder.sh pattern
+- All 6 test cases passed on first run with zero decode.sh fixes needed
+- Validated SHL-01 (single text file), SHL-02 (no-compress mode), and SHL-03 (Cyrillic UTF-8 filename)
+- Verified shell decoder produces byte-identical output to originals via SHA-256 comparison
+- Confirmed existing Rust test suite (6 tests) still passes -- no regressions
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Create shell/test_decoder.sh cross-validation test script** - `e9d7442` (test)
+2. **Task 2: Run cross-validation tests and fix any decode.sh issues** - no commit (all tests passed, no fixes needed)
+
+## Files Created/Modified
+- `shell/test_decoder.sh` - Cross-validation test script: 6 test cases covering all edge cases for shell decoder
+
+## Decisions Made
+- All 6 tests passed on first run -- decode.sh implementation from Plan 1 was correct
+- Used `sh "$DECODER"` (not `bash`) to invoke decode.sh, ensuring POSIX sh compatibility is tested
+- Followed kotlin/test_decoder.sh pattern exactly for consistency across decoder test suites
+- 7 total assertions across 6 tests (Test 2 verifies both text.txt and binary.bin)
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None.
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Shell decoder fully validated with cross-validation tests
+- Phase 5 (Shell Decoder) is complete: both decode script and test suite done
+- Phase 6 (Obfuscation) can extend decode.sh with XOR header deobfuscation and encrypted TOC parsing
+- Test script can serve as regression test when obfuscation layer is added
+
+---
+
+## Self-Check: PASSED
+
+- FOUND: shell/test_decoder.sh
+- FOUND: commit e9d7442
+- FOUND: 05-02-SUMMARY.md
+
+---
+*Phase: 05-shell-decoder*
+*Completed: 2026-02-25*