License Refresh Strategy & SQL Commands

[fupelaqu]

Story 5.7: License Refresh Strategy & SQL Commands

FRs covered: FR37, FR38
Depends on: Issue #67 (Expiry Grace Period & Degradation)
Blocking: Issue #68 (Refresh Scheduler & Telemetry)

Description

Implement the LicenseRefreshStrategy trait with two runtime-context-aware implementations, plus SHOW LICENSE and REFRESH LICENSE SQL commands.

Two Refresh Strategies

• AutoRefreshStrategy -- for long-running processes (REPL, Arrow Flight SQL, Federation). Delegates to the refresh scheduler (Story 5.8) for periodic background refresh (24h cycle).
• OnDemandRefreshStrategy -- for driver contexts (JDBC, ADBC). Fetch-once at startup (cache -> config -> backend), then cache result. NO implicit network calls during query execution. On JWT expiry mid-session: silent fallback to Community tier. Refresh only via explicit REFRESH LICENSE command.

New SQL Commands

• SHOW LICENSE -- returns license type (Community/Pro/Enterprise), quota values (max MVs, max clusters, max result rows, max concurrent queries), and expiration date (or "never" for Community)
• REFRESH LICENSE -- forces immediate license refresh from backend (API key fetch), updates in-memory license and disk cache, returns previous tier -> new tier and new expiration

Acceptance Criteria

• LicenseRefreshStrategy trait with initialize(): LicenseKey and refresh(): LicenseKey
• AutoRefreshStrategy wired for REPL/Flight SQL/Federation contexts
• OnDemandRefreshStrategy wired for JDBC/ADBC contexts -- no implicit network calls
• Expired JWT in driver context -> silent Community fallback, no error
• SHOW LICENSE parser rule (case-insensitive (?i)) producing ShowLicense query
• REFRESH LICENSE parser rule (case-insensitive (?i)) producing RefreshLicense query
• Both commands route through GatewayApi.run() like all other commands
• REFRESH LICENSE with no API key returns informational message

Technical Notes

• SQL parser rules must use (?i) regex for case-insensitivity (per Issue SQL parser SHOW/DDL/DML keywords are case-sensitive #61)
• Strategy is injected by runtime context: JDBC/ADBC -> OnDemandRefreshStrategy, REPL/Flight SQL/Federation -> AutoRefreshStrategy
• REFRESH LICENSE works in all contexts (manual override)

Related

• Issue Feature & Quota Extensions #62 -- Feature & Quota Extensions
• Issue JWT License Key Validation (Ed25519) #63 -- JWT License Key Validation
• Issue License Configuration & Resolution Priority #64 -- License Configuration & Resolution Priority
• Issue API Key Client & JWT Fetch #65 -- API Key Client & JWT Fetch
• Issue Disk Cache & Offline Fallback #66 -- Disk Cache & Offline Fallback
• Issue Expiry Grace Period & Degradation #67 -- Expiry Grace Period & Degradation (dependency)
• Issue Refresh Scheduler & Telemetry #68 -- Refresh Scheduler & Telemetry (depends on this)