fix(mcp): stop tripping simple-git block-unsafe guard on every write

[ABB65]

Problem

Every worktree write (content_save, model_save, merges) started failing on @contentrain/mcp with:

Use of "EDITOR" is not permitted without enabling allowUnsafeEditor

(or GIT_ASKPASS, PAGER, …) in any host that exports those variables — VS Code, Claude Code, CI. No Contentrain code changed: a transitive bump pulled simple-git to >= 3.34, which now bundles @simple-git/[email protected]. Its block-unsafe guard rejects a git invocation when a guard-listed variable (18 of them) is passed explicitly through .env(). The guard only scans the object handed to .env() — never the inherited process environment.

The transaction layer spread ...process.env into .env() to set the commit author, so the guard saw the host's EDITOR/GIT_ASKPASS and refused to run git commit.

Fix

Centralized in a new git/identity.ts so no future call site can reintroduce a process.env spread:

• Commit identity → -c user.name/-c user.email config (authorConfig) instead of .env(). These keys are on no unsafe list and git honours them for author + committer alike, so the guard is never touched, regardless of what the host exports. CONTENTRAIN_AUTHOR_NAME/EMAIL overrides preserved.
• networkGit (push/fetch) legitimately needs the inherited askpass/SSH/proxy environment to authenticate, so it keeps .env() but opts out of the affected guard categories via unsafe (NETWORK_UNSAFE), leaving arg-injection protections intact. This closes the same latent failure in contentrain_submit that the initial diagnosis missed (third .env() spread).
• simple-git pinned to ^3.36.0 so the dev tree matches the runtime and reproduces the guard.

Three affected call sites

Site	Before	After
transaction.ts createTransaction	.env(authorEnv())	{ config: authorConfig() }
transaction.ts mergeBranch	.env(authorEnv())	{ config: authorConfig() }
branch-lifecycle.ts networkGit	.env({ ...process.env })	+ unsafe: NETWORK_UNSAFE

Verification

• tests/git/identity.test.ts (5, new) — commits via config while EDITOR/GIT_ASKPASS are set (guard not tripped) + author/committer correct; a control asserts the old .env(process.env) path still trips the guard; networkGit-style instance runs via NETWORK_UNSAFE with a matching control.
• Existing tests/git/ suites (49) green — transaction.test.ts (commit/merge/auto-merge/selectiveSync), branch-lifecycle + remote-branches (networkGit).
• tsc --noEmit 0 errors · oxlint 0 warnings.

🤖 Generated with Claude Code

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