refactor(mode): replace config-based mode setting with runtime detection

[ayeshurun]

📥 Pull Request

✨ Description of new changes

The CLI mode (interactive/command_line) was persisted in ~/.config/fab/config.json and required fab config set mode interactive to enter REPL. Mode is now determined purely at runtime - no config entry, no explicit switching.

What changed

• Runtime detection - Context singleton exposes set_runtime_mode()/get_runtime_mode(). InteractiveCLI sets FAB_MODE_INTERACTIVE on start and resets it on exit. Everything else reads get_runtime_mode() instead of the config file.

• Config migration - init_defaults() silently removes the legacy mode key (and fab_mode) from existing config.json on first run.

• Backward compat - config get mode and config set mode <value> now print a deprecation warning and return cleanly instead of erroring.

• Context persistence - _should_use_context_file() now calls get_runtime_mode() instead of fab_state_config.get_config(FAB_MODE). Context files are still skipped in REPL (in-memory context is sufficient).

• main.py - removed the post-login block that auto-started REPL when mode=interactive was stored in config.

• Docs - modes.md rewritten to reflect the new runtime model; mode row removed from settings.md.

Entry points now

Invocation	Mode
fab	REPL (interactive)
fab <command>	Command-line

Original prompt

I want to get rid of the mode settings, where I will only have the command line and REPL modes, but not through settings. If I'm in REPL mode I want know that I'm in the context because there are some behaviors depend on that (today it is called interactive mode). I want you to also update the docs and support backward compatibility.

[ayeshurun]

@copilot Address all comments

[Copilot]

Pull request overview

Refactors Fabric CLI mode handling to remove the persisted mode setting and instead determine REPL vs command-line behavior at runtime, while keeping backward compatibility for config get/set mode and updating docs/tests accordingly.

Changes:

• Introduces a runtime-mode flag on the Context singleton and updates REPL startup/exit to toggle it.
• Removes mode from persisted config keys/defaults and adds a config migration to delete legacy mode.
• Deprecates config get/set mode (warn + no-op / runtime value), updates docs and test suites.

Reviewed changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
src/fabric_cli/core/fab_context.py	Adds runtime mode storage/accessors; switches context persistence gating to runtime mode.
src/fabric_cli/core/fab_interactive.py	Sets runtime mode when entering REPL and resets on exit.
src/fabric_cli/core/fab_constant.py	Removes mode from config-valid-values and defaults.
src/fabric_cli/core/fab_state_config.py	Adds migration logic to remove legacy mode from existing config.
src/fabric_cli/commands/config/fab_config_set.py	Deprecates config set mode and optionally launches REPL for interactive.
src/fabric_cli/commands/config/fab_config_get.py	Deprecates config get mode and returns runtime mode.
src/fabric_cli/main.py	Removes post-login auto-REPL behavior based on stored config mode.
src/fabric_cli/parsers/fab_config_parser.py	Updates examples away from mode.
tests/conftest.py	Resets Context runtime mode between tests to prevent leakage.
tests/test_core/test_fab_context.py	Adds unit tests for runtime mode behavior and config removal assertions.
tests/test_core/test_context_persistence.py	Updates persistence tests to rely on runtime mode instead of config mode.
tests/test_core/test_fab_state_config.py	Adds migration tests for removing legacy mode in init_defaults().
tests/test_core/test_fab_config_completers.py	Updates completer tests to avoid mode.
tests/test_commands/test_config.py	Updates command tests for deprecation behavior and non-mode config set/get.
docs/essentials/modes.md	Rewrites docs to describe runtime-detected REPL vs command-line.
docs/essentials/settings.md	Removes mode from persisted settings documentation.
.github/instructions/test.instructions.md	Updates documented test naming convention/examples.
.changes/unreleased/optimization-20260322-103653.yaml	Adds changelog entry for the optimization/refactor.

Comments suppressed due to low confidence (1)

tests/test_core/test_fab_state_config.py:79

• There’s a redundant local import json inside test_init_defaults_no_write_when_unchanged even though the module now imports json at the top. Removing the inner import will reduce noise and keep imports consistent.

    def test_init_defaults_no_write_when_unchanged(self, tmp_path, monkeypatch):
        """Test that init_defaults skips writing when config already has all defaults."""
        import json

        from fabric_cli.core import fab_constant

[Copilot]

Pull request overview

Copilot reviewed 18 out of 18 changed files in this pull request and generated 2 comments.