clear claude_session_id on recurring task completion

[bborbe]

Summary

• Recurring task completion now clears claude_session_id before writing the file
• New ClearClaudeSessionID() method on TaskFrontmatter (delegates to FrontmatterMap.Delete)
• Non-recurring task completion is unchanged (claude_session_id is part of the historical record there)
• Spec: specs/in-progress/015-recurring-task-clears-claude-session-id.md

Why

Daily recurring tasks were inheriting the previous run's session ID. A real vault task had carried the same claude_session_id for ~5 weeks of daily completions — corrupts any tooling that trusts the field to identify the current session.

Test plan

• make precommit (passes locally)
• New Describe("ClearClaudeSessionID") in pkg/domain/task_frontmatter_test.go (set+clear path; absent-key no-op)
• New It("clears claude_session_id after completion") in pkg/ops/complete_test.go recurring-daily context
• Test asserts Get("claude_session_id") == nil — kills the SetClaudeSessionID("") shortcut
• Existing non-recurring tests untouched and passing

[ben-s-pull-request-reviewer]

PR Review Report: clear claude_session_id on recurring task completion

Files Changed

• CHANGELOG.md — release note for the bugfix
• pkg/domain/task_frontmatter.go — adds ClearClaudeSessionID() method
• pkg/domain/task_frontmatter_test.go — direct unit tests for the new method
• pkg/ops/complete.go — calls ClearClaudeSessionID() in handleRecurringTask
• pkg/ops/complete_test.go — integration test verifying the key is absent post-completion

---

Must Fix (Critical)

None.

Should Fix (Important)

1. pkg/domain/task_frontmatter.go:177, 234, 430 — Three errors.Wrapf calls use no format placeholder:

   • Line 177: errors.Wrapf(ctx, validation.Error, "unknown task phase '%s'", value) — %s appears twice in the string literal but is not a printf placeholder; the value argument is passed but ignored.
   • Line 234: errors.Wrapf(ctx, err, "invalid priority") — same issue, no format args.
   • Line 430: errors.Wrapf(ctx, validation.Error, "unknown task status '%s'", value) — same.

   Fix: use errors.Wrap(ctx, ...) or fix the format string. (Pre-existing issue in unchanged code, not introduced by this PR but flagging per guidelines.)

Nice to Have (Optional)

None.

---

Plan Concerns — Resolved

Concern	Resolution
ClearClaudeSessionID() delegates to Delete() — verifies Get() returns nil (absent) not "" (present-but-empty)	✅ Confirmed: Delete removes the key; Get returns nil for absent keys. Test uses Get() not ClaudeSessionID() — correct.
ClearClaudeSessionID() only in handleRecurringTask, not in non-recurring paths	✅ Only handleRecurringTask (line 169) exists in this file. No handleNonRecurringTask or handleSingleTask to worry about.
Test sets session ID before calling Complete	✅ BeforeEach at line 276 calls task.SetClaudeSessionID("test-session-uuid") before JustBeforeEach — not vacuous.
SetClaudeSessionID("") redundancy after this change	✅ SetClaudeSessionID("") stores "" as a value (key present); ClearClaudeSessionID() deletes the key. Distinct semantics, no conflict.

---

Verdict

{
  "verdict": "approve",
  "summary": "The feature is well-implemented: ClearClaudeSessionID() uses Delete() (not Set+empty) so Get() returns nil, the call is correctly scoped to handleRecurringTask only, tests verify both presence and absence paths, and the GoDoc clearly distinguishes key-removal semantics from store-empty-string. Three pre-existing errors.Wrapf calls without format placeholders exist in the file but are not introduced by this changeset.",
  "comments": [
    {
      "file": "pkg/domain/task_frontmatter.go",
      "line": 177,
      "severity": "major",
      "message": "errors.Wrapf: format placeholder '%s' appears in the string literal but is not a printf directive; 'value' argument is passed but ignored. Use errors.Wrap(ctx, validation.Error, \"unknown task phase '\"+value+\"'\") or fmt.Errorf. (Pre-existing, not introduced by this PR.)"
    },
    {
      "file": "pkg/domain/task_frontmatter.go",
      "line": 234,
      "severity": "major",
      "message": "errors.Wrapf: no format arguments provided to a Wrapf call. Use errors.Wrap(ctx, err, \"invalid priority\"). (Pre-existing, not introduced by this PR.)"
    },
    {
      "file": "pkg/domain/task_frontmatter.go",
      "line": 430,
      "severity": "major",
      "message": "errors.Wrapf: same issue as line 177 — '%s' in the string literal is not a printf placeholder; 'value' argument is passed but unused. Use errors.Wrap or fix the format string. (Pre-existing.)"
    }
  ],
  "concerns_addressed": [
    "correctness: ClearClaudeSessionID() uses Delete() — Get() returns nil (absent), not \"\" (present-but-empty); test assertion uses Get() which is correct",
    "correctness: ClearClaudeSessionID() is only called from handleRecurringTask; no handleNonRecurringTask or handleSingleTask exists to pollute",
    "tests: BeforeEach sets session ID via SetClaudeSessionID() before JustBeforeEach calls Complete — not a vacuous pass",
    "correctness: SetClaudeSessionID(\"\") keeps store-empty semantics; ClearClaudeSessionID() uses Delete(); distinct methods, no redundancy"
  ]
}