Compare two configs

What differs between config.yaml and prod.yaml? Save the structured differences as diff.json.

The task

The reference answer shows the job can be done with deft. It is not an agent run.

deft yaml diff config.yaml prod.yaml --json > diff.json

Input

config.yaml 125 B

service:
  name: billing
  port: 8080
  debug: true
database:
  host: localhost
  pool: 5
features:
  - invoices
  - refunds

prod.yaml 65 B

service:
  port: 80
  debug: false
database:
  host: db.internal

Reference output

diff.json 581 B

{"v":1,"ok":true,"op":"yaml.diff","items":[{"ok":true,"inputs":["config.yaml","prod.yaml"],"outputs":[],"facts":{"equal":false,"changes":[{"path":".service.name","kind":"removed","before":"billing"},{"path":".service.port","kind":"changed","before":8080,"after":80},{"path":".service.debug","kind":"changed","before":true,"after":false},{"path":".database.host","kind":"changed","before":"localhost","after":"db.internal"},{"path":".database.pool","kind":"removed","before":5},{"path":".features","kind":"removed","before":["invoices","refunds"]}]},"warnings":[]}],"elapsed_ms":0}

How a result is judged (1 check)

python: code = "t = open('diff.json').read(); assert 'service.port' in t"

Runs

CodexWithout deftPassed2026-11-07

Time: 19s
New tokens: 4.6k
Total input: 54.5k
Output tokens: 0.7k
Commands: 3
Failed: 1

Trace

I’ll read both YAML files, compare their parsed structures, and write the differences to `diff.json` in the current directory.
pwd && rg --files -g 'config.yaml' -g 'prod.yaml' -g 'AGENTS.md'
output
```
prod.yaml
config.yaml
```

cat config.yaml && cat prod.yaml && python3 -c 'import yaml; print(\"pyyaml available\")' (exit 1)

output

service:
  name: billing
  port: 8080
  debug: true
database:
  host: localhost
  pool: 5
features:
  - invoices
  - refunds
service:
  port: 80
  debug: false
database:
  host: db.internal
Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'yaml'

cat > diff.json <<'EOF' { \"differences\": [ { \"path\": \"service.name\", \"type\": \"removed\", \"config\": \"billing\" }, { \"path\": \"service.port\", \"type\": \"changed\", \"config\": 8080, \"prod\": 80 }, { \"path\": \"service.debug\", \"type\": \"changed\", \"config\": true, \"prod\": false }, { \"path\": \"database.host\", \"type\": \"changed\", \"config\": \"localhost\", \"prod\": \"db.internal\" }, { \"path\": \"database.pool\", \"type\": \"removed\", \"config\": 5 }, { \"path\": \"features\", \"type\": \"removed\", \"config\": [ \"invoices\", \"refunds\" ] } ] } EOF cat diff.json
output
```
{
  "differences": [
    {
      "path": "service.name",
      "type": "removed",
      "config": "billing"
    },
    {
      "path": "service.port",
      "type": "changed",
      "config": 8080,
      "prod": 80
    },
    {
      "path": "service.debug",
      "type": "changed",
      "config": true,
      "prod": false
    },
    {
      "path": "database.host",
      "type": "changed",
      "config": "localhost",
      "prod": "db.internal"
    },
    {
      "path": "database.pool",
      "type": "removed",
      "config": 5
    },
    {
      "path": "features",
      "type": "removed",
      "config": [
        "invoices",
        "refunds"
      ]
    }
  ]
}
```
Found six differences between `config.yaml` and `prod.yaml`, and saved them in [diff.json](diff.json). Three values changed; `service.name`, `database.pool`, and `features` appear only in `config.yaml`.

Output

diff.json 679 B

{
  "differences": [
    {
      "path": "service.name",
      "type": "removed",
      "config": "billing"
    },
    {
      "path": "service.port",
      "type": "changed",
      "config": 8080,
      "prod": 80
    },
    {
      "path": "service.debug",
      "type": "changed",
      "config": true,
      "prod": false
    },
    {
      "path": "database.host",
      "type": "changed",
      "config": "localhost",
      "prod": "db.internal"
    },
    {
      "path": "database.pool",
      "type": "removed",
      "config": 5
    },
    {
      "path": "features",
      "type": "removed",
      "config": [
        "invoices",
        "refunds"
      ]
    }
  ]
}

CodexWith deft, skill installedPassedRead the skillUsed deft2026-11-07

Time: 19s
New tokens: 8.8k
Total input: 86.7k
Output tokens: 0.6k
Commands: 5
Failed: 0

Trace

I’ll inspect both YAML files and save their structured differences to `diff.json` in the current directory.

cat .agents/skills/deft/SKILL.md && rg --files -g 'config.yaml' -g 'prod.yaml' -g 'AGENTS.md'

output

---
name: deft
description: "Use deft first for any simple, direct operation on local files, whatever the type: convert, read, extract, edit, compress, merge, split, compare or inspect. Try it before writing a script or one-liner. If unsure, run deft find; if it says no command does this, use another tool. Not for programming work: to read, write or change source code, skip it."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, adjust, montage, OCR
- `video`: Trim, merge, convert, compress, subtitles, GIF, frames (ffmpeg)
- `audio`: Convert, trim, normalize, denoise, cut silence (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline
- `sheet`: Excel/CSV/ODS tables: SQL query, pivot, merge, split, convert
- `json`: JSON: convert, format, merge, diff, validate
- `toml`: TOML: convert, format, merge, diff, validate
- `xml`: XML: convert, format, merge, diff, validate
- `yaml`: YAML: convert, format, merge, diff, validate
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word and PDF
- `epub`: E-books: info, to text, Markdown and PDF
- `gps`: GPX and KML tracks: convert, distance and time
- `qr`: Create QR codes and barcodes; r
… 722 more characters

deft yaml --help

output

deft yaml - commands (input -> output)
  convert   yaml -> data       Change format: --to json|toml|xml|jsonl
  diff      yaml... -> report  Compare two files by structure
  format    yaml -> yaml       Tidy a file: --sort-keys
  merge     yaml... -> yaml    Deep-merge files; later files win
  validate  yaml -> report     Check syntax, or a JSON Schema with --schema
More: deft yaml <command> --help

deft yaml diff --help && deft yaml diff config.yaml prod.yaml --json

output

deft yaml diff - Compare two files by structure

Usage: deft yaml diff <yaml>... [-o <json>] [options]
In: yaml (all together, in order)   Out: printed result
Key order and formatting do not count.
Common: -o --force --dry-run --json -j   (deft help common)

Examples:
  deft yaml diff config.yaml override.yaml

Result fields: equal, changes
{"v":1,"ok":true,"op":"yaml.diff","items":[{"ok":true,"inputs":["config.yaml","prod.yaml"],"outputs":[],"facts":{"equal":false,"changes":[{"path":".service.name","kind":"removed","before":"billing"},{"path":".service.port","kind":"changed","before":8080,"after":80},{"path":".service.debug","kind":"changed","before":true,"after":false},{"path":".database.host","kind":"changed","before":"localhost","after":"db.internal"},{"path":".database.pool","kind":"removed","before":5},{"path":".features","kind":"removed","before":["invoices","refunds"]}]},"warnings":[]}],"elapsed_ms":2}

deft yaml diff config.yaml prod.yaml -o diff.json --force

output

ok yaml.diff config.yaml prod.yaml -> diff.json  6 changes  0.00s

cat diff.json

output

{
  "equal": false,
  "changes": [
    {
      "path": ".service.name",
      "kind": "removed",
      "before": "billing"
    },
    {
      "path": ".service.port",
      "kind": "changed",
      "before": 8080,
      "after": 80
    },
    {
      "path": ".service.debug",
      "kind": "changed",
      "before": true,
      "after": false
    },
    {
      "path": ".database.host",
      "kind": "changed",
      "before": "localhost",
      "after": "db.internal"
    },
    {
      "path": ".database.pool",
      "kind": "removed",
      "before": 5
    },
    {
      "path": ".features",
      "kind": "removed",
      "before": [
        "invoices",
        "refunds"
      ]
    }
  ]
}

Saved the structured differences in [diff.json](diff.json). There are six differences: `service.name`, `database.pool`, and `features` were removed; `service.port`, `service.debug`, and `database.host` changed.

Output

diff.json 702 B

{
  "equal": false,
  "changes": [
    {
      "path": ".service.name",
      "kind": "removed",
      "before": "billing"
    },
    {
      "path": ".service.port",
      "kind": "changed",
      "before": 8080,
      "after": 80
    },
    {
      "path": ".service.debug",
      "kind": "changed",
      "before": true,
      "after": false
    },
    {
      "path": ".database.host",
      "kind": "changed",
      "before": "localhost",
      "after": "db.internal"
    },
    {
      "path": ".database.pool",
      "kind": "removed",
      "before": 5
    },
    {
      "path": ".features",
      "kind": "removed",
      "before": [
        "invoices",
        "refunds"
      ]
    }
  ]
}

Claude Opus 5.5Without deftPassed2026-11-07

Time: 12s
New tokens: 9.3k
Total input: 42.4k
Output tokens: 0.8k
Commands: 0
Failed: 0

Trace

Output

diff.json 483 B

{
  "base": "config.yaml",
  "compare": "prod.yaml",
  "changed": [
    { "path": "service.port", "config": 8080, "prod": 80 },
    { "path": "service.debug", "config": true, "prod": false },
    { "path": "database.host", "config": "localhost", "prod": "db.internal" }
  ],
  "only_in_config": [
    { "path": "service.name", "value": "billing" },
    { "path": "database.pool", "value": 5 },
    { "path": "features", "value": ["invoices", "refunds"] }
  ],
  "only_in_prod": []
}

Claude Opus 5.5With deft, skill installedPassedRead the skillUsed deft2026-11-07

Time: 14s
New tokens: 10.6k
Total input: 75.3k
Output tokens: 0.8k
Commands: 0
Failed: 0

Trace

Output

.claude/skills/deft/SKILL.md 2.1 KB

---
name: deft
description: "Use deft first for any simple, direct operation on local files, whatever the type: convert, read, extract, edit, compress, merge, split, compare or inspect. Try it before writing a script or one-liner. If unsure, run deft find; if it says no command does this, use another tool. Not for programming work: to read, write or change source code, skip it."
---

# deft

One local command for file jobs. Prefer it over writing Python or shell scripts.

Syntax: `deft <group> <command> [inputs] [-o output] [--options]`

Groups:
- `pdf`: Merge, split, compress, encrypt, forms, OCR, compare, convert
- `image`: Resize, crop, convert, compress, adjust, montage, OCR
- `video`: Trim, merge, convert, compress, subtitles, GIF, frames (ffmpeg)
- `audio`: Convert, trim, normalize, denoise, cut silence (ffmpeg)
- `doc`: Word/ODT/RTF: to text, Markdown, HTML, PDF; find and replace
- `slides`: PowerPoint: extract text, Markdown outline
- `sheet`: Excel/CSV/ODS tables: SQL query, pivot, merge, split, convert
- `json`: JSON: convert, format, merge, diff, validate
- `toml`: TOML: convert, format, merge, diff, validate
- `xml`: XML: convert, format, merge, diff, validate
- `yaml`: YAML: convert, format, merge, diff, validate
- `md`: Markdown to PDF, HTML, Word, EPUB; table of contents
- `html`: HTML to Markdown, text, Word and PDF
- `epub`: E-books: info, to text, Markdown and PDF
- `gps`: GPX and KML tracks: convert, distance and time
- `qr`: Create QR codes and barcodes; read QR codes

How to use it:
1. Run `deft <group>` to list commands, or `deft find "<what you want>"` to search. If it says `no command does this`, use another tool.
2. Run `deft <group> <command> --help` for options and examples.
3. `deft convert <in> -o <out.ext>` converts between formats by extension.
4. Results are one line starting with `ok`, `partial` or `error`; add `--json` to parse them. Errors include a `hint:` with the fix.

Inputs are never overwritten; pass `--force` or `--in-place` to allow it. Globs and directories work as inputs; several inputs run in parallel.

If `deft` is not installed, ask the user, then follow https://github.com/firstprayer/deft/blob/main/docs/INSTALL.md

diff.json 702 B

{
  "equal": false,
  "changes": [
    {
      "path": ".service.name",
      "kind": "removed",
      "before": "billing"
    },
    {
      "path": ".service.port",
      "kind": "changed",
      "before": 8080,
      "after": 80
    },
    {
      "path": ".service.debug",
      "kind": "changed",
      "before": true,
      "after": false
    },
    {
      "path": ".database.host",
      "kind": "changed",
      "before": "localhost",
      "after": "db.internal"
    },
    {
      "path": ".database.pool",
      "kind": "removed",
      "before": 5
    },
    {
      "path": ".features",
      "kind": "removed",
      "before": [
        "invoices",
        "refunds"
      ]
    }
  ]
}

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