v0.13.0

Agentic Harness v0.13.0

Version 0.13.0 adds fail-closed, verified multi-approach execution and an
official Grok Build worker profile without weakening the v0.12 assurance
contracts.

Verified Best-of-N

• Adds agentic-harness best-of-n and the equivalent
  verified-best-of-n alias for two to ten concurrent candidates.
• Runs every candidate from the same commit, immutable GoalSpec, and frozen
  verification command set in an isolated Git worktree.
• Hashes pre-existing verifier inputs and disqualifies candidates that alter
  them, even when the altered check exits successfully.
• Selects only from independently verified non-empty patches, applies the
  smallest verified patch deterministically, and runs the same checks again in
  the original workspace.
• Rolls back the applied patch and reports blocked if final verification fails,
  errors, or cannot be preserved durably.
• Stores private, checksummed candidate patches and a versioned tournament
  receipt under .agentic-harness/tournaments/.

GUI

• Adds a plain-language Implementation approaches choice to the embedded
  GUI: one approach for speed or three verified approaches for stronger search.
• Runs tournaments in the existing background task lifecycle with cooperative
  stop behavior, durable progress, recovery that fails closed after an
  interrupted process, and a final result backed by the tournament verifier.
• Shows the number of approaches and winning candidate in public task evidence;
  managed external routes remain single-approach unless their own contract
  explicitly supports tournaments.

Grok Build

• Adds agentic-harness init-agent grok and a Grok Build Settings option.
• Uses Grok Build's documented headless grok -p interface with plain output,
  bounded turns, automatic updates disabled, and its OS-enforced workspace
  sandbox.
• Denies git push and sudo shell commands in the starter profile. Grok
  still owns its credentials and provider traffic, and headless edits require
  bypass permissions inside the bounded workspace; this is not a local-only
  execution path.

Compatibility and assurance

• No GoalSpec, evidence-v2, assurance-mode, or amendment schema changes.
• Existing single-worker CLI and GUI paths retain their prior behavior.
• High-assurance tournament specification approval remains explicitly blocked
  rather than silently downgraded.
• Git worktrees isolate candidate changes but are not a general security
  boundary for arbitrary external agents. Use each agent's supported OS sandbox
  and review its tool policy.