What each exit code means, what goes to stdout versus stderr, and how to script against both.

Exit codes

Code	Meaning	Emitted by
`0`	Success	every command
`1`	An error: invalid configuration, a missing artifact, a failed run, an unreachable endpoint	every command
`2`	A check failed — the tool worked, and the answer is no	`validate`, `apply`, `config --check`

The distinction between 1 and 2 is load-bearing in scripts:

handbook validate --skill skills/api --source ~/code/api
case $? in
  0) echo "fresh" ;;
  2) echo "the handbook has drifted — schedule a resync" ;;
  *) echo "something is broken" >&2; exit 1 ;;
esac

Which commands can exit 2

validate — the SKILL package failed a structural check, or source hashes moved.
apply — one or more edits did not land (no-match, ambiguous, unsafe-path, …). In --dry-run this means "this plan would not apply cleanly".
config --check — a setting is invalid or a required one is missing.

plan exits 1 when the planner gave up, not 2: an abandoned run is an error, not a negative answer.

stdout versus stderr

Stream	Carries
stdout	The command's result, as JSON — except `plan` without `--out`, which writes the plan itself, and `config` without `--json`, which writes a table
stderr	All logging, all progress, all warnings, and every error message

That split is what makes piping safe:

handbook analyze --source ~/code/api --work work/api | jq .functions
handbook config --json | jq '.settings[] | select(.source.kind == "env") | .key'
handbook plan --source ~/code/api --request "…" > plan.md     # logs still visible

Errors are prefixed so they are greppable:

handbook: error: invalid configuration:
  - source is required: pass --source, set HANDBOOK_GENERATE_SOURCE, or add it to handbook.config.yaml

Log levels

How	Level
default	`info`
`-v` / `--verbose`	`debug`
`-q` / `--quiet`	`error` — wins over `-v`
`HANDBOOK_LOG_LEVEL=debug`	`debug`, without a flag

HANDBOOK_LOG_LEVEL also affects the two bootstrap lines that report which .env files and which config file were loaded — useful when a value is coming from somewhere you did not expect.

Result shapes

analyze

{
  "language": "multi",
  "files": 412,
  "functions": 3187,
  "edgesKept": 9042,
  "edgesDropped": 611,
  "filesUnparsed": 3
}

generate

{
  "phasesRun": ["1", "2a", "2b", "2c", "3"],
  "nCards": 412,
  "nStages": 9,
  "nUnassignedFiles": 0,
  "nRegisters": 6,
  "usage": { "promptTokens": 1840221, "completionTokens": 214880, "totalTokens": 2055101 }
}

render

{
  "outDir": "work/api/handbook",
  "nStagePages": 9,
  "agent": { "...": "…" },
  "html": { "...": "…" },
  "htmlSingle": { "...": "…" },
  "llms": { "...": "…" }
}

skill

{
  "outDir": "skills/api",
  "nStagePages": 9,
  "references": [
    "agent/index.md",
    "agent/symbols.tsv",
    "agent/files.tsv",
    "agent/calls.tsv",
    "agent/stages/stage-1.md",
    "…",
    "overview.md",
    "index.md",
    "registers.md",
    "coverage.json"
  ]
}

plan (with --out)

{
  "out": "plan.md",
  "turns": 11,
  "declarations": { "willModify": ["Uploader.send"], "willAdd": ["Uploader._retry"], "willRemove": [] }
}

apply

{
  "ok": true,
  "dryRun": false,
  "outcomes": [
    { "index": 1, "file": "src/upload.py", "where": "Uploader.send (~88)", "status": "applied", "line": 88 }
  ],
  "changedFiles": ["src/upload.py"],
  "backupDir": "/repo/.handbook-patches/2026-08-08T14-05-11-204Z",
  "problems": []
}

resync

{
  "skipped": false,
  "changedFiles": ["src/upload.py"],
  "addedFiles": [],
  "deletedFiles": [],
  "affectedStages": ["stage-3"],
  "cardsRegenerated": 1,
  "narrated": true,
  "rendered": ["…"]
}

validate is the exception: it writes human-readable lines to stderr and communicates through its exit code.

Exit codes and output

Exit codes

Which commands can exit 2

stdout versus stderr

Log levels

Result shapes

On this page