1-- subject_length_warn.lua
 2-- Warns when your subject line is getting too long.
 3-- Most email clients truncate subjects beyond ~60 characters.
 4--
 5-- Thresholds are configurable in Settings → Plugins.
 6
 7local matcha = require("matcha")
 8
 9local cfg = matcha.settings({
10    enabled = {
11        type = "boolean",
12        default = true,
13        label = "Enable subject length warnings",
14    },
15    soft_limit = {
16        type = "number",
17        default = 60,
18        label = "Soft limit (chars)",
19        description = "Warn that the subject may truncate above this length.",
20    },
21    hard_limit = {
22        type = "number",
23        default = 78,
24        label = "Hard limit (chars)",
25        description = "Warn that the subject is too long above this length.",
26    },
27})
28
29matcha.on("composer_updated", function(state)
30    if not cfg.enabled then
31        return
32    end
33    local len = #state.subject
34    if len > cfg.hard_limit then
35        matcha.set_status("composer", "Subject too long (" .. len .. " chars)")
36    elseif len > cfg.soft_limit then
37        matcha.set_status("composer", "Subject may truncate (" .. len .. " chars)")
38    end
39end)