2. State the methods every rebindable seam must implement (docs only)

[nikolaystrikhar]

What: adds a "What each seam must implement" section to docs/extending.md carrying the signatures and contract for all six rebindable interfaces, and corrects what the same file says about Absorber::all() and about container failures.

Usage:

class My_Checker implements Checker_Interface {
    public function is_active( string $basename ): bool { /* … */ }
    public function is_network_active( string $basename ): bool { /* … */ }
}

Why this way:

A doc that tells a host to rebind a seam has to name the seam's methods. It recommended rebinding Checker_Interface while listing neither of its two, and an omission there is a fatal at class-declaration time for anyone who followed the advice without opening src/.

Signatures alone would not be enough, so each method carries its contract. That is_network_active() must be false off multisite because callers skip their own is_multisite() guard, that the activation record is written after the callback returns — what a plausible implementation gets wrong silently.

Summary by CodeRabbit

• Documentation
  • Expanded extension guidance with implementation requirements for replaceable components.
  • Documented method responsibilities, execution order, error handling, and multisite behavior.
  • Clarified container binding during application startup.
  • Added details on configuration error handling and preserved underlying error information.
  • Clarified type references and merge-notice behavior.

[nikolaystrikhar]

@coderabbitai review

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Enterprise

Run ID: 25217328-1edb-4909-8554-6fe85df26a80

📥 Commits

Reviewing files that changed from the base of the PR and between 45e1c11 and 1fb5ec1.

📒 Files selected for processing (1)

• docs/extending.md

🚧 Files skipped from review as they are similar to previous changes (1)

• docs/extending.md

Included review availability: Your plan provides up to 12 included reviews per hour; 2 remain after this review.

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📝 Walkthrough

Walkthrough

The extension guide now defines implementation contracts for replaceable seams, multisite behavior, boot-time container binding, and configuration error handling.

Changes

Extension contracts and boot behavior

Layer / File(s)	Summary
Replaceable seam contracts docs/extending.md	The guide documents registrar, notice-writer, deactivator, and checker requirements, including ordering, filtering, multisite behavior, and failure consequences.
Resolver and activator execution docs/extending.md	The guide documents resolver request and capability gates, processing order, redirects, exits, activator callbacks, and once-ever completion tracking.
Container binding and error handling docs/extending.md	The guide documents ContainerInterface binding during boot and expanded exception behavior for invalid bindings and container construction failures.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 1fb5e

This documentation-only change introduces no runtime or production behavior changes, so no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: d4mation

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the documentation change to define methods for each rebindable seam.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch 41-seam-signatures

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