Add a console output backend for condensed deploy output

[enichols]

What

• Add a console output backend that condenses a deploy into a header panel, per-phase sections, live per-host status lines, and an end-of-run summary — opt in with output: { console: {} }.
• Suppress the raw SSHKit firehose on screen while it's active (routed to a null sink, still teed to other backends like file); -v/--verbose restores it.
• Render concurrent per-host spinners on a TTY (tty-spinner/pastel), with a deterministic line-based fallback for non-TTY/CI.

Why

A full deploy buries prompts and errors under a wall of interleaved SSHKit output; this gives an at-a-glance view of progress while keeping any failure — and the failing host's retained output — prominent. It's built as an opt-in backend on the existing output framework and reconstructed entirely from the line stream every backend already receives (phase markers, host-tagged lines, the modify.kamal exception payload), so it adds no deploy-path coupling and leaves current behavior unchanged when off.

Testing

• bin/test test/output/console_logger_test.rb test/configuration/output_test.rb → 20 runs, 0 failures.
• Full unit suite → 850 runs, 3 failures — all three reproduce on clean main (git-email and Docker/arch env issues), none from this change.
• rubocop on all changed files → clean.
• Previewed success and failure runs in both plain and TTY (PTY) modes.
• Docker integration tests not run (require a running daemon).

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Composed with Claude Code (Opus 4.8)

[Copilot]

Pull request overview

Adds an opt-in console output backend that renders a condensed deploy view (header + per-phase progress + per-host results + summary), including a TTY spinner renderer and a deterministic non-TTY renderer. This plugs into the existing output framework and wires CLI markers / SSHKit stream metadata into the console backend.

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Changes:

• Introduces Kamal::Output::ConsoleLogger plus plain/TTY renderers for condensed deploy output.
• Adds console to output configuration + documentation and extends CLI/SSHKit wiring to support marker/host/severity context.
• Adds pastel and tty-spinner dependencies and tests for the new backend.

Reviewed changes

Copilot reviewed 11 out of 12 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
test/output/console_logger_test.rb	Adds unit coverage for console backend rendering and failure attribution.
test/configuration/output_test.rb	Verifies console backend configuration, settings validation, and enablement.
lib/kamal/output/console/tty_renderer.rb	Implements interactive TTY spinner rendering per phase/host.
lib/kamal/output/console/renderer.rb	Adds shared formatting/panel helpers and color handling for console renderers.
lib/kamal/output/console/plain_renderer.rb	Implements deterministic, line-based rendering for non-TTY/CI output.
lib/kamal/output/console_logger.rb	Core console backend: reconstructs phases/host statuses and emits summary + retained output.
lib/kamal/configuration/output.rb	Registers console as a valid output logger type.
lib/kamal/configuration/docs/output.yml	Documents the new output.console settings and behavior.
lib/kamal/commander.rb	Routes SSHKit formatter output to a null sink when console backend is enabled.
lib/kamal/cli/base.rb	Tags say markers with thread-local color metadata for the console backend.
kamal.gemspec	Adds runtime deps for TTY rendering (pastel, tty-spinner).
Gemfile.lock	Locks the new dependencies and their transitive requirements.

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[Copilot]

Pull request overview

Copilot reviewed 11 out of 12 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

lib/kamal/commander.rb:228

• When @console_output is enabled, @null_output = File.open(File::NULL, "w") will overwrite any previously-open null sink without closing it first (and the else branch never closes it when switching back). If output is configured more than once in a process, this will leak FDs; it also keeps the sink open even after the command finishes. Consider closing any existing sink before replacing it, and closing+nil’ing it when console output is not active.

      if @console_output
        @null_output = File.open(File::NULL, "w")
        SSHKit.config.output = Kamal::Output::Formatter.new(@null_output, output_logger)
      else
        SSHKit.config.output = Kamal::Output::Formatter.new($stdout, output_logger)
      end

[enichols]

Example output via a script that simulates a deploy, minus the colors. Successful deploy :

bundle exec ruby script/console_output_demo.rb 2>/dev/null

╭─ deploy ─────────────────────────────────────────╮
│ showtime@9f2c1ab → 3 hosts, 2 roles · production │
╰──────────────────────────────────────────────────╯

┌ ❯ Build and push app image
└── [✔] 172.16.0.1 0.8s

┌ ❯ Ensure kamal-proxy is running
├── [✔] 172.16.0.1 0.4s
├── [✔] 172.16.0.2 0.4s
└── [✔] 172.16.0.3 0.4s

┌ ❯ Detect stale containers
├── [✔] 172.16.0.1 0.4s
├── [✔] 172.16.0.2 0.4s
└── [✔] 172.16.0.3 0.4s

┌ ❯ Start container
├── [✔] 172.16.0.1 0.7s
├── [✔] 172.16.0.2 0.7s
└── [✔] 172.16.0.3 0.7s

┌ ❯ Prune old containers and images
├── [✔] 172.16.0.1 0.4s
├── [✔] 172.16.0.2 0.4s
└── [✔] 172.16.0.3 0.4s

╭─ Summary ─────╮
│ ✔ 3 ok   3.4s │
╰───────────────╯

..and one with a failure :

bundle exec ruby script/console_output_demo.rb --fail 2>/dev/null

╭─ deploy ─────────────────────────────────────────╮
│ showtime@9f2c1ab → 3 hosts, 2 roles · production │
╰──────────────────────────────────────────────────╯

┌ ❯ Build and push app image
└── [✔] 172.16.0.1 0.8s

┌ ❯ Ensure kamal-proxy is running
├── [✔] 172.16.0.1 0.4s
├── [✔] 172.16.0.2 0.4s
└── [✔] 172.16.0.3 0.4s

┌ ❯ Detect stale containers
├── [✔] 172.16.0.1 0.4s
├── [✔] 172.16.0.2 0.4s
└── [✔] 172.16.0.3 0.4s

┌ ❯ Start container
├── [✔] 172.16.0.1 1.0s
├── [✔] 172.16.0.2 1.0s
└── [✖] 172.16.0.3 failed

╭─ Summary ───────────────────╮
│ ✔ 2 ok   ✖ 1 failed   3.1s  │
│ needs attention: 172.16.0.3 │
╰─────────────────────────────╯

── retained output · 172.16.0.3 ─────
┃ kamal-proxy is already running
┃ no stale containers
┃ docker run --detach ... showtime:9f2c1ab
┃ Container health check failed after 30s
┃ docker logs: FATAL: could not connect to database