fix(validate): catch workspace setup_error causes at validate-time

[christso]

Closes #1078

Problem

agentv validate passed eval files that would fail at runtime with setup_error when workspace hook scripts or template paths didn't exist. These errors are detectable statically.

Changes

New validateWorkspacePaths() function in packages/core/src/evaluation/validation/workspace-path-validator.ts. Called alongside validateFileReferences for all eval files.

What it catches

1. Hook script paths — command args that look like relative file paths (./, ../, or script extensions: .mjs, .js, .ts, .sh, .py, etc.) are resolved using the same cwd precedence as the runtime:

hook.cwd ?? workspaceFileDir ?? evalDir

If the resolved path doesn't exist → error.

2. workspace.template — the template path is resolved and checked for existence.

Both checks apply to inline workspace: objects and to paths inside external workspace files (workspace: "path.yaml").

What it doesn't flag

• System binaries (node, bash, etc.) — no path separator or script extension
• String arguments without script extensions (-c, echo hello, etc.)

Red/Green UAT

RED — hook script missing:

$ agentv validate bad-hook.eval.yaml

Validation Summary
✗ bad-hook.eval.yaml
  ✗ [workspace.hooks.before_all.command] Hook script not found: ../../scripts/eval-config/setup.mjs (resolved to /scripts/eval-config/setup.mjs)

RED — template missing:

$ agentv validate bad-template.eval.yaml

Validation Summary
✗ bad-template.eval.yaml
  ✗ [workspace.template] Template path not found: ./nonexistent-template (resolved to /tmp/agentv-test-uat/nonexistent-template)

GREEN — valid eval, no workspace:

$ agentv validate good.eval.yaml

Validation Summary
✓ good.eval.yaml
Total files: 1  Valid: 1  Invalid: 0

Tests

10 new unit tests covering all cases: no workspace, valid/missing workspace file ref, valid/missing template, valid/missing hook script, system binary (not flagged), hook cwd resolution, external workspace file hooks.

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View logs

[christso]

Post-review fixes applied

Addressed code review findings:

• Combined duplicate imports from node:fs/promises into one line
• Fixed JSDoc — changed "two classes, listed three" to correctly list two items, and added a note that external file existence is owned by eval-validator
• Removed redundant existence check for workspace string references — eval-validator.ts already catches this and emits an error that gates the extra validation from running at all. My validator now silently skips when it can't read the file (eval-validator will have already reported the error)
• Added arg index to error location — workspace.hooks.before_all.command[1] instead of workspace.hooks.before_all.command, matching the convention used by file-reference-validator
• Added .bash and .zsh extensions to looksLikeFilePath heuristic
• Added test coverage for: after_each/after_all hook names, deprecated script alias, template path inside external workspace file

Regarding the hook.cwd resolution concern: The reviewer suggested the runtime resolves hook.cwd against process.cwd(), but this is incorrect — yaml-parser.ts:parseWorkspaceScriptConfig pre-resolves relative cwd values against the eval file directory (or workspace file directory for external files) at parse time, which is exactly what this validator does. Resolution is correct.