feat: add slack api command

[mwbrooks]

Changelog

Added slack api <method> [key=value ...] [flags] command for calling any Slack API method directly from the Slack CLI.

Examples:

• slack api chat.postMessage channel=C123 text="hi"
• slack api chat.postMessage '{"channel":"C123","text":"hi"}'

Summary

Adds a new top-level slack api command that lets users call any Slack API method without leaving the terminal.

Key features:

• Token resolution
  1. --token flag
  2. --app flag
  3. SLACK_BOT_TOKEN env var
  4. SLACK_USER_TOKEN env var
  5. App Prompt (only in project)
• Body Format Auto-detection:
  • Form-Encoded: slack api chat.postMessage channel=C123 text="hi"
  • JSON: slack api chat.postMessage '{"channel":"C123","text":"hi"}'
• Body Format Flags: --json <string> and --data <string>
  • Form-Encoded: slack api chat.postMessage --data 'channel=C123 text="hi"'
  • JSON: slack api chat.postMessage --json '{"channel":"C123","text":"hi"}'
• HTTP Options Flags
  • Method override (-X)
  • Custom headers (-H)
  • Show Response headers (--include)
• Output formatting
  • Pretty-printed JSON in TTY
  • Compact for piped output / scripting
• Retry support
  • Automatic retry on 429/503 with Retry-After

Open Questions

• I originally had support for a team prompt, but removed it because it uses our Slack CLI tooling token, which has limited scope access. Sounds good?

Preview

$ slack api auth.test --token xoxb-...
{
    "ok": true,
    "url": "https://myworkspace.slack.com/",
    "team": "My Workspace",
    "user": "bot",
    "team_id": "T12345",
    "user_id": "U12345"
}

Post Message as Form Data (with app selection prompt):

2026-05-10-slack-cli-api-1.mov

Post Message as JSON (with app selection prompt):

2026-05-10-slack-cli-api-2.mov

Post Message with Custom Token --token:

2026-05-10-slack-cli-api-3.mov

JSON Responses are Pretty-Printed in TTY:

2026-05-10-slack-cli-api-5.mov

JSON Responses are Condense in Scripting/Non-TTY:

2026-05-10-slack-cli-api-4.mov

--include All Response Headers:

2026-05-10-slack-cli-api-6.mov

Testing

• slack api --help - shows correct token priority and examples
• slack api auth.test --token xoxb-... - returns auth info
• slack api auth.test --app local - installs app and uses bot token (in project)
• SLACK_BOT_TOKEN=xoxb-... slack api auth.test - uses env var (outside project)
• slack api auth.test - prompts interactively when no flags/env set (in project)
• slack api chat.postMessage channel=C123 text="hi" - sends form-encoded body
• slack api chat.postMessage '{"channel":"C123","text":"hi"}' - auto-detects JSON
• slack api auth.test --include - shows HTTP status and response headers
• slack api auth.test | cat - outputs compact JSON (non-TTY)
• go test ./cmd/api/... ./internal/api/... - all unit tests pass

Requirements

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

❌ Patch coverage is 81.46552% with 43 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.52%. Comparing base (59d720d) to head (d7a032c).

Files with missing lines	Patch %	Lines
cmd/api/api.go	86.20%	13 Missing and 11 partials ⚠️
internal/api/raw_request.go	66.66%	11 Missing and 8 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #538      +/-   ##
==========================================
+ Coverage   71.30%   71.52%   +0.21%     
==========================================
  Files         222      224       +2     
  Lines       18695    18927     +232     
==========================================
+ Hits        13331    13537     +206     
- Misses       4184     4190       +6     
- Partials     1180     1200      +20     

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[srtaalej]

This is looking great! ⭐ thanks for adding the test commands in the description 🫂
the command is working great except

lack api auth.test | cat

the test implies there should be JSON output but slack api auth.test is an interactive prompt so it errors out instead. perhaps we update the pr description? the command should be
lack api auth.test --token xoxb-... | cat
lack api auth.test --app A... | cat
right?

[srtaalej]

qq: does this cover retries on both 429 and 503 returns 🤔

[srtaalej]

left 2 testing-related comments/ questions but this is working great ! ⭐ ⭐ ⭐ such a handy command