Demo 46: Code Replay & Explainable Agent

> /replay list

Agent Session Traces
════════════════════

ID                    │ Date                │ Duration │ Task                          │ Events
──────────────────────┼─────────────────────┼──────────┼───────────────────────────────┼───────
sess-20260329-001     │ 2026-03-29 09:14:02 │ 45s      │ Fix auth test failures        │ 12
sess-20260328-003     │ 2026-03-28 16:42:18 │ 2m 13s   │ Refactor DB connection pool   │ 28
sess-20260328-002     │ 2026-03-28 14:05:33 │ 1m 07s   │ Add pagination to /users API  │ 19
sess-20260328-001     │ 2026-03-28 10:22:45 │ 32s      │ Update README badges          │ 7
sess-20260327-002     │ 2026-03-27 15:38:10 │ 3m 44s   │ Implement rate limiting       │ 34

Showing 5 of 23 sessions. Use `/replay list --all` for full history.

> /replay sess-20260329-001

Replaying: sess-20260329-001 — "Fix auth test failures"
Started: 2026-03-29 09:14:02 | Duration: 45s | Events: 12

[1/12] 09:14:02  USER_MESSAGE
  "Fix the failing auth tests"

[2/12] 09:14:03  REASONING
  The user wants me to fix failing auth tests. I should first run the
  test suite to identify which tests are failing and examine the error
  messages.

[3/12] 09:14:04  TOOL_CALL  → shell
  Command: cargo test auth:: 2>&1
  Result: 2 tests failed (test_login, test_token_refresh)

[4/12] 09:14:08  REASONING
  Two tests failed: test_login and test_token_refresh. Both show
  InvalidCredentials errors. Let me read the auth module to understand
  the validation logic.

[5/12] 09:14:09  TOOL_CALL  → read_file
  Path: src/auth.rs
  Lines read: 1-120

[6/12] 09:14:10  REASONING
  I see the issue. The validate_user function checks the password
  hash before verifying the email exists. If the email lookup fails,
  it returns InvalidCredentials instead of UserNotFound, and the
  hash comparison panics on None.

[7/12] 09:14:11  TOOL_CALL  → edit_file
  Path: src/auth.rs
  Change: Reorder validation — check email existence first
  Lines modified: 45-52

[8/12] 09:14:12  TOOL_CALL  → edit_file
  Path: src/auth.rs
  Change: Add early return for missing user
  Lines modified: 46-48

[9/12] 09:14:13  TOOL_CALL  → shell
  Command: cargo test auth:: 2>&1
  Result: 4 tests passed, 0 failed ✓

[10/12] 09:14:18  REASONING
  All auth tests pass now. Let me run the full suite to check for
  regressions.

[11/12] 09:14:19  TOOL_CALL  → shell
  Command: cargo test 2>&1
  Result: 47 tests passed, 0 failed ✓

[12/12] 09:14:44  RESPONSE
  Fixed 2 failing auth tests by reordering validation logic in
  src/auth.rs. The email existence check now runs before password
  hash comparison.

Replay complete.

> /explain sess-20260329-001

Explainable Agent — sess-20260329-001
═════════════════════════════════════

Task: Fix auth test failures

Decision Chain:
  1. DIAGNOSE → Ran test suite to identify failures
     Rationale: Need to see exact errors before reading code
     Alternatives considered: Read code first (rejected — test output is more targeted)

  2. INVESTIGATE → Read src/auth.rs
     Rationale: Both failures point to validation logic in the auth module
     Files considered: src/auth.rs, src/models/user.rs (auth.rs chosen — errors originate there)

  3. ROOT CAUSE → Validation order bug
     Finding: Password hash checked before email existence verified
     Confidence: High (error message matches code path)

  4. FIX → Reorder validation + add early return
     Approach: Minimal change — only reorder existing checks
     Alternatives: Add separate email validation function (rejected — over-engineering)

  5. VERIFY → Ran full test suite
     Result: 47/47 passed, no regressions
     Rationale: Full suite needed to catch side effects of validation order change

Risk Assessment:
  Regression risk: Low (validation order change is isolated)
  Behavioral change: UserNotFound error now returned instead of InvalidCredentials
                     when email is missing (more correct behavior)

Cost: $0.012 | Tokens: 3,241 | Tool calls: 5

> /replay search --file src/auth.rs

Sessions involving src/auth.rs:
  sess-20260329-001  │ Fix auth test failures        │ edited lines 45-52
  sess-20260325-004  │ Add OAuth2 support             │ edited lines 88-134
  sess-20260320-002  │ Implement JWT refresh          │ edited lines 60-75

3 sessions found.

> /replay search --tool edit_file --since 7d

Sessions with edit_file calls (last 7 days):
  14 sessions, 42 total file edits across 18 unique files.
  Most edited: src/auth.rs (3 sessions), src/api/routes.rs (2 sessions)

> /replay export sess-20260329-001 --format markdown

Exported: .vibecli/traces/exports/sess-20260329-001-report.md

Contents:
  - Task summary
  - Full reasoning chain
  - All file diffs
  - Test results before/after
  - Cost breakdown

> /replay compare sess-20260329-001 sess-20260325-004

Session Comparison
══════════════════

                     │ sess-20260329-001         │ sess-20260325-004
─────────────────────┼───────────────────────────┼──────────────────────────
Task                 │ Fix auth test failures    │ Add OAuth2 support
Duration             │ 45s                       │ 3m 22s
Tool calls           │ 5                         │ 14
Files edited         │ 1                         │ 4
Lines changed        │ +6 -3                     │ +89 -12
Tests before         │ 45/47 (2 failing)         │ 47/47 (all passing)
Tests after          │ 47/47                     │ 52/52 (5 new)
Cost                 │ $0.012                    │ $0.067
Strategy             │ Diagnose → Fix → Verify   │ Plan → Implement → Test → Verify

Common files: src/auth.rs
Approach difference: First session was a targeted bug fix (minimal change).
Second session was feature addition (new code paths, new tests).