docs(operations): document subscription-only autonomous-tick path post Agent SDK credit (AISDLC-353)

[deefactorial]

Summary

Documents the /ai-sdlc orchestrator-tick subscription-only autonomous loop as the preferred zero-incremental-cost dispatch path post-2026-06-15, when the Agent SDK credit change makes cli-orchestrator tick --spawner claude (cron/daemon) draw from the $200/mo credit pool.

The key insight: because /ai-sdlc orchestrator-tick runs the Agent tool call inside an interactive Claude Code session turn (not a non-interactive Agent SDK invocation), it draws from the operator's interactive Max-20x quota rather than the Agent SDK credit pool. As long as one Claude Code session stays alive, the loop churns the backlog at zero incremental cost above the subscription fee.

Changes

• docs/operations/billing-and-cost-optimization.md: new §1b with full architecture explanation, operator quickstart (3 commands), side-by-side comparison table vs --spawner claude cron path, cost-projection table at 20 tasks/day throughput, and failure-mode/recovery docs.
• TL;DR table: new row for the zero-incremental-cost path.
• ai-sdlc-plugin/commands/orchestrator-tick.md: updated description frontmatter to call out the subscription-only billing path and cross-reference billing doc §1b.
• CLAUDE.md "Canonical execution paths" table: new row for the autonomous loop; annotated --spawner claude row to note Agent SDK credit draw post-2026-06-15.
• pipeline-cli/docs/spawner.md: cross-referenced subscription-only path as preferred high-throughput alternative in the --spawner claude row.
• Task file: moved from backlog/tasks/ to backlog/completed/.

Failure-mode coverage

Documents session crash recovery: worktrees survive, AISDLC-242 recoverable-abort detection, operator restarts session and fires the command again.

Test plan

• Verify billing doc §1b renders correctly (headings, tables, code blocks)
• Verify orchestrator-tick.md description frontmatter is valid YAML
• Verify CLAUDE.md table row alignment
• Verify spawner.md cross-reference link is correct
• Confirm docs-only changeset auto-approves via AISDLC-215 pre-push hook

🤖 Generated with Claude Code

[github-actions]

AI-SDLC: Reviewer Agents Skipped (Anthropic Budget Exhausted)

1/3 review agents failed with HTTP 400 invalid_request_error
("credit balance is too low"). The remaining agent(s) either succeeded or were
skipped by the AISDLC-141 conditional classifier. Since every reviewer that
DIDN'T succeed only failed due to budget, the noisy CHANGES_REQUESTED has been
suppressed.

What this means:

• This PR has been only partially reviewed by the automated agents.
• Branch protection still requires ai-sdlc/pr-ready (the rollup gate),
  but the Post Review Results status was posted as success so the gate
  does not deadlock.
• A human reviewer should manually validate this PR before merging,
  or top up the Anthropic API credit balance and push again to re-trigger.

Posted by AI-SDLC Review Agents — AISDLC-147 budget circuit breaker (AISDLC-157 broadened gate)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[github-actions]

AI-SDLC: Reviewer Agents Skipped (Local Attestation Valid)

A valid DSSE attestation envelope was found at
.ai-sdlc/attestations/<HEAD-sha>.dsse.json for this commit. The 3 review
agents were already run locally via /ai-sdlc execute and the verdict was
cryptographically signed against:

• Per-file content hash (contentHashV3)
• Review policy hash
• Reviewer agent file hashes
• Plugin version

CI re-running the same 3 agents would produce the same verdict at the cost
of ~3 Anthropic API invocations. Per AISDLC-147 patch 1, we trust the local
attestation as a SOFT signal and skip the duplicate review.

Note: Attestation remains AUDIT-ONLY as a merge gate (per AISDLC-140 sub-4).
The re-actors/alls-green aggregator (ai-sdlc/pr-ready) is the single merge gate.

Posted by AI-SDLC Review Agents — AISDLC-147 attestation cost-saver

[github-actions]

Auto-approved by valid local DSSE attestation (AISDLC-147 patch 1).