[J. Nick Koston (bdraco)]

Description

Documents AutomationList and build_automation_lists for a hub that fires its own automations, such as a keypad's on_key: each automation is a pointer-sized slot (4 bytes on 32-bit chips) in a list sized at build time, with no Trigger object, and an unused list compiles out. It also adds a row to the "When to use which method" table.

Pull request in esphome this documents (if applicable):

• [core] Add AutomationList for hubs that trigger their own automations esphome#21788

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[Copilot]

🟡 Changes recommended

The Python example registers on_tag without a corresponding C++ implementation, so configuring it generates a call to the nonexistent add_on_tag_automation() and causes compilation to fail.

1 open issue

• Fix Python on_tag registration mismatch · New

What changed in this PR

Adds developer guidance for hubs that fire their own automations using AutomationList, documenting the API introduced in esphome/esphome#21788.

Changes:

• Adds Python registration and C++ dispatch examples using build-time-sized automation lists.
• Explains memory usage, conditional compilation, and when to prefer callbacks or per-automation stored values.
• Extends the method-selection table with a hub-owned event example.

File	Description
src/​content/​docs/​architecture/​components/​automations.md	Documents AutomationList and build_automation_lists, with examples and method-selection guidance.

_{Review effort: Balanced}

[J. Nick Koston (bdraco)]

ESPHome Bot (@esphbot) review

[ESPHome Bot (esphbot)]

Previous review — superseded by a newer review below.

[ESPHome Bot (esphbot)]

Tip

No blocking issues found — ready to merge.

[ESPHome Bot (esphbot)]

Note

No code changes since the last review (e89fb7c) — skipping. Push new commits or re-request a review to run again.

[J. Nick Koston (bdraco)]

ESPHome Bot (@esphbot) review

[ESPHome Bot (esphbot)]

PR Review — Document AutomationList for hubs that fire their own automations

Merge-ready. Both earlier findings are fixed, and only one small, non-blocking nit is left.

What works well:

• d888e8f fixes the earlier slot-size suggestion. The text now says each automation takes "one pointer-sized slot (4 bytes on 32-bit chips)", which is also correct for the 64-bit host platform.
• e89fb7c fixes Copilot's on_tag mismatch. The Python _AUTOMATION_LISTS entry and the C++ add_on_key_automation setter now line up.
• The C++ example puts the setter, the dispatch and the member behind #ifdef MY_HUB_ON_KEY_COUNT. That shows clearly how an unused list compiles out.
• The text tells readers when to use something else: a callback when other code listens to the same event, and new_automation when each automation needs its own stored value. It also says to check empty() before building an argument that is costly to make.
• The section follows the page's existing structure (a description, then #### Python, then #### C++) and adds a matching row to the method table.

One nit:

• The pending wiegand row links to a dev file that does not use AutomationList yet. The pending lock row uses plain text with only the PR link instead.

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Checklist

• Python and C++ examples are consistent (setter name matches add_<conf_key>_automation)
• Prior review feedback (on_tag mismatch, pointer-sized slot) resolved
• Pending upstream links clearly marked and consistent with other pending rows
• Diff matches PR description

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Automated review by Kōan (Claude) HEAD=d888e8f 28s

[ESPHome Bot (esphbot)]

Tip

No blocking issues found — ready to merge.

[Copilot]

🟢 Approval recommended

The documentation change covering hub-owned automation lists has no active review issues.

No open issues 🎉

1 resolved since last review

• Fix Python on_tag registration mismatch

_{Review effort: Balanced}