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/STATE.md

@@ -5,22 +5,22 @@
 See: .planning/PROJECT.md (updated 2026-02-24)
 
 **Core value:** Archive impossible to unpack without knowing the format -- standard tools (7z, tar, unzip, binwalk) cannot recognize or extract contents
-**Current focus:** Phase 5 in progress (Shell Decoder)
+**Current focus:** Phase 5 complete (Shell Decoder). Ready for Phase 6.
 
 ## Current Position
 
-Phase: 5 of 6 (Shell Decoder)
-Plan: 1 of 2 in current phase
-Status: Plan 1 complete, Plan 2 (cross-validation tests) remaining
-Last activity: 2026-02-25 -- Busybox-compatible shell decoder script (shell/decode.sh)
+Phase: 5 of 6 (Shell Decoder) -- COMPLETE
+Plan: 2 of 2 in current phase (all done)
+Status: Phase 5 complete -- both decoder and cross-validation tests done
+Last activity: 2026-02-25 -- Cross-validation tests for shell decoder (shell/test_decoder.sh)
 
-Progress: [███████░░░] 70%
+Progress: [████████░░] 80%
 
 ## Performance Metrics
 
 **Velocity:**
-- Total plans completed: 7
-- Average duration: 4.1 min
+- Total plans completed: 8
+- Average duration: 3.9 min
 - Total execution time: 0.5 hours
 
 **By Phase:**
@@ -31,10 +31,10 @@ Progress: [███████░░░] 70%
 | 2. Core Archiver | 2/2 | 6 min | 3 min |
 | 3. Round-Trip Verification | 2/2 | 8 min | 4 min |
 | 4. Kotlin Decoder | 1/1 | 4 min | 4 min |
-| 5. Shell Decoder | 1/2 | 3 min | 3 min |
+| 5. Shell Decoder | 2/2 | 5 min | 2.5 min |
 
 **Recent Trend:**
-- Last 5 plans: 2min, 3min, 5min, 4min, 3min
+- Last 5 plans: 3min, 5min, 4min, 3min, 2min
 - Trend: stable
 
 *Updated after each plan completion*
@@ -72,6 +72,8 @@ Recent decisions affecting current work:
 - Phase 5: Graceful HMAC degradation when openssl lacks -mac support
 - Phase 5: Extract ciphertext to temp file before decryption (avoids pipe buffering issues)
 - Phase 5: LC_ALL=C for predictable byte handling across locales
+- Phase 5: All 6 cross-validation tests passed on first run -- decode.sh was correct as written
+- Phase 5: Used sh (not bash) to invoke decode.sh in tests for POSIX compatibility validation
 
 ### Pending Todos
 
@@ -86,5 +88,5 @@ None yet.
 ## Session Continuity
 
 Last session: 2026-02-25
-Stopped at: Completed 05-01-PLAN.md (Shell decoder script; Phase 5 Plan 1 of 2)
+Stopped at: Completed 05-02-PLAN.md (Shell decoder cross-validation tests; Phase 5 complete)
 Resume file: None