v4-best-practices

V4 Best Practices

Rules for multi-step V4 thinking-mode workflows. Each rule prevents a specific, observable failure class.

1. Verify references before writing

Before referencing a file path, function, or type in code or plan output, call grep_files or read_file to confirm it exists in the workspace.

# Bad:  edit_file path="src/config/loader.rs" (assumed from memory)
# Good: grep_files pattern="pub fn load_config" → confirms src/config/mod.rs:42
#        then reference src/config/mod.rs:42

Failure avoided: edit_file errors on non-existent paths; LSP diagnostics on hallucinated symbols.

2. Spawn a verifier sub-agent before multi-file execution

Before executing a plan that touches 3+ files, spawn a deepseek-v4-flash sub-agent (thinking off) to read the target files and confirm path/symbol assumptions still hold.

agent type="verifier" model="deepseek-v4-flash"
  prompt: "Read these files and confirm: [list assumptions]. Report mismatches."

Failure avoided: multi-step edits fail partway because file structure changed since the plan was drafted.

3. Plan output must use confirmed path:line references

In plan-mode output, replace vague location pointers with path:line references drawn from a prior grep_files result.

# Bad:  "Update the retry logic in the client module"
# Good: "Update retry loop at crates/engine/src/client.rs:187"

Failure avoided: agent-mode execution cannot locate the intended edit target when plan directions are imprecise.