feat(interactive): add fzf-style fuzzy finder for USE statement

[apstndb]

Summary

• Add interactive fuzzy finder (fzf-style) triggered by configurable key binding (default: Ctrl+T)
• MVP: USE <database> context — lists databases from current instance, pre-fills query with typed prefix, replaces argument on selection
• Upgrade go-multiline-ny v0.21.0 → v0.22.4, go-readline-ny v1.9.1 → v1.14.1

New system variables

Variable	Default	Description
CLI_ENABLE_FUZZY_FINDER	true	Enable/disable fuzzy finder
CLI_FUZZY_FINDER_KEY	C_T	Key binding (uses go-readline-ny key names)

Behavior

USE apst<Ctrl+T>
# → fzf opens with "apst" as initial query
# → select apstndb-sampledb-with-data-idx
USE apstndb-sampledb-with-data-idx

TODO (future phases)

• Metadata caching with TTL
• Extend to SHOW TABLES, SHOW COLUMNS FROM, SHOW INDEX FROM
• Preview window with DDL/column info
• System variable completion for SET

Test plan

• make check passes (test + lint + fmt-check)
• TestDetectFuzzyContext covers USE context detection with various inputs
• Manual verification with real Spanner instance

🤖 Generated with Claude Code

[gemini-code-assist]

Summary of Changes

Hello @apstndb, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances the interactive command-line interface by integrating a fuzzy finder. This feature streamlines the process of selecting database names when issuing USE statements, improving user efficiency and overall experience. The implementation includes flexible configuration options through new system variables and updated core dependencies to support the new interactive capabilities.

Highlights

• Interactive Fuzzy Finder: Introduced an fzf-style fuzzy finder for USE <database> statements, allowing users to quickly select database names from the current instance.
• Configurable Key Binding: The fuzzy finder is triggered by a configurable key binding, defaulting to Ctrl+T, and uses go-readline-ny key names.
• New System Variables: Added two new system variables: CLI_ENABLE_FUZZY_FINDER (default true) to enable/disable the feature, and CLI_FUZZY_FINDER_KEY (default C_T) to customize the key binding.
• Dependency Updates: Upgraded go-multiline-ny from v0.21.0 to v0.22.4 and go-readline-ny from v1.9.1 to v1.14.1, and added go-fuzzyfinder along with related terminal UI dependencies.

Changelog

• go.mod
  • Upgraded github.com/hymkor/go-multiline-ny to v0.22.4.
  • Added github.com/ktr0731/go-fuzzyfinder at v0.9.0.
  • Updated github.com/mattn/go-runewidth to v0.0.19.
  • Upgraded github.com/nyaosorg/go-readline-ny to v1.14.1.
  • Added indirect dependencies for terminal UI components, including github.com/clipperhouse/uax29/v2, github.com/gdamore/encoding, github.com/gdamore/tcell/v2, github.com/ktr0731/go-ansisgr, github.com/lucasb-eyer/go-colorful, github.com/nsf/termbox-go, and github.com/nyaosorg/go-ttyadapter.
• go.sum
  • Added and updated checksums for new and upgraded Go module dependencies.
• internal/mycli/cli_readline.go
  • Integrated the fuzzy finder command into the interactive readline editor.
  • Added logic to bind the fuzzy finder to a configurable key (CLI_FUZZY_FINDER_KEY) if the feature is enabled (CLI_ENABLE_FUZZY_FINDER).
  • Included logging for instances where an unknown key name is provided for the fuzzy finder binding.
• internal/mycli/fuzzy_finder.go
  • Added a new file implementing the core logic for the fuzzyFinderCommand.
  • Implemented detectFuzzyContext to analyze the current input buffer and identify USE statement contexts.
  • Provided fetchCandidates and fetchDatabaseCandidates functions to retrieve available database names from the current Spanner instance.
  • Managed terminal handoff for the fuzzy finder UI and replaced the input buffer with the user's selection.
• internal/mycli/fuzzy_finder_test.go
  • Added a new file containing unit tests for the detectFuzzyContext function, covering various USE statement inputs.
• internal/mycli/main_test.go
  • Updated existing test cases within Test_initializeSystemVariables to reflect the default values of the newly introduced EnableFuzzyFinder and FuzzyFinderKey system variables.
• internal/mycli/system_variables.go
  • Defined new boolean field EnableFuzzyFinder and string field FuzzyFinderKey within the systemVariables struct.
  • Set default values for EnableFuzzyFinder to true and FuzzyFinderKey to C_T in newSystemVariablesWithDefaults.
• internal/mycli/var_registry.go
  • Registered the new system variables CLI_ENABLE_FUZZY_FINDER and CLI_FUZZY_FINDER_KEY with their respective types and descriptions in the variable registry.

Activity

• The make check command passed, indicating successful execution of tests, linting, and format checks.
• The TestDetectFuzzyContext function was added to cover various inputs for USE context detection.
• Manual verification of the fuzzy finder functionality was performed with a real Spanner instance.
• The pull request was generated with Claude Code.

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[github-actions]

Code Metrics Report

📊 View detailed coverage report (available for 7 days)

	main (124c9ea)	#506 (8610f06)	+/-
Coverage	70.0%	69.4%	-0.6%
Code to Test Ratio	1:1.2	1:1.2	-0.1
Test Execution Time	1m4s	1m13s	+9s

Details

  |                     | main (124c9ea) | #506 (8610f06) |  +/-  |
  |---------------------|----------------|----------------|-------|
- | Coverage            |          70.0% |          69.4% | -0.6% |
  |   Files             |             54 |             55 |    +1 |
  |   Lines             |           5704 |           5762 |   +58 |
+ |   Covered           |           3997 |           4004 |    +7 |
- | Code to Test Ratio  |          1:1.2 |          1:1.2 |  -0.1 |
  |   Code              |          13118 |          13244 |  +126 |
+ |   Test              |          16510 |          16622 |  +112 |
- | Test Execution Time |           1m4s |          1m13s |   +9s |

Code coverage of files in pull request scope (82.3% → 74.6%)

Files	Coverage	+/-	Status
internal/mycli/cli_readline.go	52.2%	-2.9%	modified
internal/mycli/fuzzy_finder.go	10.2%	+10.2%	added
internal/mycli/system_variables.go	95.0%	0.0%	modified
internal/mycli/var_registry.go	90.6%	+0.0%	modified

---

Reported by octocov

[gemini-code-assist]

Code Review

This pull request introduces an interactive fuzzy finder for the USE statement. While the feature significantly improves the interactive experience, there are critical logic errors in how the input context is detected and how the buffer is manipulated in multiline scenarios. Specifically, the context detection logic currently assumes the USE statement is at the very beginning of the entire multiline buffer, and the buffer replacement logic uses absolute offsets that will cause incorrect behavior or panics when the cursor is not on the first line. Additionally, a missing regular expression reference (extractDatabaseRe) will lead to compilation or runtime failures. These issues must be addressed to ensure the feature works reliably in a multiline editor environment.

[apstndb]

/gemini summary

[gemini-code-assist]

Summary of Changes

This pull request introduces a significant enhancement to the interactive command-line interface by adding a fuzzy finder. This feature aims to improve user experience and efficiency by providing an intuitive way to select database names, reducing manual typing and potential errors. The changes involve integrating new libraries, updating existing ones, and implementing the core logic for context detection and candidate presentation, all while maintaining configurability for the end-user.

Highlights

• Interactive Fuzzy Finder for USE statements: An fzf-style fuzzy finder has been integrated, allowing users to interactively select database names when typing USE <database> commands. This feature is triggered by a configurable key binding, defaulting to Ctrl+T.
• Configurable System Variables: Two new system variables, CLI_ENABLE_FUZZY_FINDER (default true) and CLI_FUZZY_FINDER_KEY (default C_T), have been introduced to control the fuzzy finder's activation and key binding.
• Dependency Updates and Additions: Key dependencies go-multiline-ny and go-readline-ny were upgraded, and go-fuzzyfinder along with several terminal UI-related indirect dependencies were added to support the new interactive functionality.
• Context-Aware Database Selection: The fuzzy finder intelligently detects the USE statement context, pre-fills the query with any typed prefix, and replaces the argument with the selected database name.

Changelog

• go.mod
  • Upgraded github.com/hymkor/go-multiline-ny from v0.21.0 to v0.22.4.
  • Added github.com/ktr0731/go-fuzzyfinder at v0.9.0.
  • Updated github.com/mattn/go-runewidth from v0.0.16 to v0.0.19.
  • Upgraded github.com/nyaosorg/go-readline-ny from v1.9.1 to v1.14.1.
  • Removed golang.org/x/exp as a direct dependency, now an indirect dependency.
  • Added new indirect dependencies for terminal UI components, including github.com/clipperhouse/uax29/v2, github.com/gdamore/encoding, github.com/gdamore/tcell/v2, github.com/ktr0731/go-ansisgr, github.com/lucasb-eyer/go-colorful, github.com/nsf/termbox-go, and github.com/nyaosorg/go-ttyadapter.
• go.sum
  • Updated checksums for all modified and newly added Go module dependencies.
• internal/mycli/cli_readline.go
  • Integrated the fuzzyFinderCommand into the interactive readline editor.
  • Added logic to bind the fuzzy finder to the CLI_FUZZY_FINDER_KEY if CLI_ENABLE_FUZZY_FINDER is enabled.
  • Included a warning log for unknown key names configured for the fuzzy finder binding.
• internal/mycli/fuzzy_finder.go
  • Added a new file implementing the core logic for the fuzzyFinderCommand.
  • Implemented detectFuzzyContext to analyze the current input buffer and identify USE statement contexts.
  • Provided fetchCandidates and fetchDatabaseCandidates functions to retrieve available database names from the current Spanner instance.
  • Managed terminal handoff for the fuzzy finder UI and replaced the input buffer with the user's selection.
• internal/mycli/fuzzy_finder_test.go
  • Added a new file containing unit tests for the detectFuzzyContext function, covering various USE statement inputs.
• internal/mycli/main_test.go
  • Updated existing test cases within Test_initializeSystemVariables to reflect the default values of the newly introduced EnableFuzzyFinder and FuzzyFinderKey system variables.
• internal/mycli/system_variables.go
  • Defined new boolean field EnableFuzzyFinder and string field FuzzyFinderKey within the systemVariables struct.
  • Set default values for EnableFuzzyFinder to true and FuzzyFinderKey to C_T in newSystemVariablesWithDefaults.
• internal/mycli/var_registry.go
  • Registered the new system variables CLI_ENABLE_FUZZY_FINDER and CLI_FUZZY_FINDER_KEY with their respective types and descriptions in the variable registry.

Activity

• Gemini Code Assist provided an initial summary of changes.
• Gemini Code Assist reported code metrics, noting a slight decrease in overall coverage but an increase in covered lines and files.
• Gemini Code Assist provided critical feedback regarding context detection and extractDatabaseRe definition in fuzzy_finder.go.
• The author, apstndb, acknowledged and fixed the issues raised by Gemini Code Assist in commit 4a451f4.