Handles Redis string commands.

Each handler takes the uppercased command name, a list of string arguments, and an injected store map. Returns plain Elixir terms — the connection layer handles RESP encoding.

Supported commands

• GET key — returns the value or nil

• SET key value [EX secs | PX ms | EXAT unix-sec | PXAT unix-ms] [NX | XX] [GET] [KEEPTTL] — sets a key with optional expiry/conditions

• DEL key [key ...] — deletes keys, returns count deleted
• EXISTS key [key ...] — returns count of existing keys
• MGET key [key ...] — returns list of values (nil for missing)
• MSET key value [key value ...] — sets multiple keys atomically
• INCR key — increment integer value by 1
• DECR key — decrement integer value by 1
• INCRBY key increment — increment integer value by given amount
• DECRBY key decrement — decrement integer value by given amount
• INCRBYFLOAT key increment — increment float value by given amount
• APPEND key value — append to value, return new length
• STRLEN key — return byte length of value
• GETSET key value — set key, return old value
• GETDEL key — get value and delete atomically

• GETEX key [EX s | PX ms | EXAT ts | PXAT ms-ts | PERSIST] — get and update TTL

• SETNX key value — set if not exists
• SETEX key seconds value — set with expiry in seconds
• PSETEX key milliseconds value — set with expiry in milliseconds
• GETRANGE key start end — return substring by byte range
• SETRANGE key offset value — overwrite part of string at offset
• MSETNX key value [key value ...] — set multiple only if none exist