[SaladDay]

This is D2b protocol PR 1, the Runtime–Harness boundary. One Environment will soon serve several Sessions in sequence. To prepare for that, each Session's native Harness state now lives only under directories derived from its state key, agent.StateDir(StateRoot|RuntimeRoot, kind, key). While there is one Session per Runtime, nothing else changes. An installation must be reinstalled, not upgraded.

Paths

Harness	Native path	New location
Codex	CODEX_HOME	<StateRoot>/runtime/codex/state/<key>
Codex	SQLite home	<RuntimeRoot>/runtime/codex/state/<key>
Claude Code, with a workspace	CLAUDE_CONFIG_DIR	<StateRoot>/runtime/claude_sdk/state/<key>/config
Claude Code, with a workspace	HOME, TMPDIR	home and scratch under <RuntimeRoot>/runtime/claude_sdk/state/<key>
Claude Code, environment: none	CLAUDE_CONFIG_DIR, HOME, TMPDIR, working directory	config, home, tmp and work under <StateRoot>/runtime/claude_sdk/state/<key>. HOME used to be the daemon's shared home, where the native CLI writes its MCP logs.
MiniMax Code	native state	already compliant

Deleted

• Codex's private allocSessionDir and its path sanitizer.
• Claude Code's per-Runtime directory fields and WorkspaceConfig.
• The single-use helpers workspaceDirs and workspaceEnvironment.
• DiscoveryOptions.Profile, which no adapter reads after this change.
• The stale daemon/agent-sessions and profile-level runtime entries in the unlabelled-state check.
• Test cases that never ran.

The Claude readiness check now runs with a temporary HOME, TMPDIR and CLAUDE_CONFIG_DIR, which it discards afterwards.

Docs

• The rule is in contracts/agents-api/harness-onboarding.md (Register the adapter), with its zh mirror.
• The Codex and Claude guides state only the new paths and link to the rule.

Verification

• A blind review found one Medium (Claude's environment: none HOME) and six Low issues. All are fixed.
• go test passes on agent/... and cli. A new two-key test asserts disjoint directories and that the native environment points into them, including environment: none.
• go vet, check-runtime-contract, check-harness-catalog and check-translations pass.

---

^{Open in [code]smith · Need help on this PR? Tag @codesmith-bot with what you need.}