Replace lyaml with api7-lua-tinyyaml and prepare the 0.1.0 releasev0.1.0

lyaml binds the system libyaml, which luarocks does not vendor, so
installing the rock failed wherever that library was absent, taking the
whole extension down on a stock macOS machine. api7-lua-tinyyaml is pure
Lua and matches lyaml on every quoting, escaping and block-scalar form
profiles use.

What the subset costs: anchors and aliases are not resolved, and plain
multi-line scalars raise. The raise surfaces through the existing parse
warning, but an unresolved alias came back as the literal "*alias"
string and would have become a profile name, so frontmatter.parse now
detects those keys, drops them, and warns.

Point source.url at code.tjp.lol with a v0.1.0 tag, replacing a GitHub
URL that never existed. Add a LICENSE file and mise release tasks, and
fix the README dependency-install command, which called a luarocks.cmd
function that does not exist.

1 files changed, 39 insertions, 5 deletions

diff --git a/subagents/frontmatter.lua b/subagents/frontmatter.lua
index 94fe2ac..8740870 100644
--- a/subagents/frontmatter.lua
+++ b/subagents/frontmatter.lua
@@ -13,8 +13,9 @@
 --     (a lone `---` at the top of a prose file is a horizontal rule, not a
 --      broken header, so this case is deliberately silent)
 --   * empty fenced block        -> empty mapping, no warning
---   * lyaml missing or erroring -> body after the fence, warning returned
+--   * parser missing or erroring-> body after the fence, warning returned
 --   * YAML document not a map   -> body after the fence, warning returned
+--   * unresolved anchor/alias   -> that key dropped, warning returned
 --
 -- In the warning cases the fenced block is dropped rather than folded back
 -- into the body: an unparseable header is noise the child agent should not be
@@ -27,6 +28,34 @@ local function trim(s)
     return (s:gsub("^%s+", ""):gsub("%s+$", ""))
 end
 
+-- tinyyaml parses a subset of YAML: it does not resolve anchors (`&a`) or
+-- aliases (`*a`). Rather than failing on them it hands back the raw token as
+-- a plain string, so `name: *base` arrives here as the literal "*base" and
+-- would sail through any `type(v) == "string"` check to become a profile's
+-- actual name. Detect that shape and drop those keys so the caller falls back
+-- to its defaults instead of adopting a bogus value.
+--
+-- The match is deliberately narrow -- a whole value that is exactly `*word`,
+-- or one opening with `&word ` -- so ordinary prose containing `*` or `&`
+-- (`'fetch & parse'`, `'a *b* c'`) is left alone.
+local function strip_unresolved_aliases(data)
+    local hits = {}
+    for k, v in pairs(data) do
+        if type(v) == "string"
+            and (v:match("^%*[%w_%-]+$") or v:match("^&[%w_%-]+%s")) then
+            hits[#hits + 1] = tostring(k)
+        end
+    end
+    if #hits == 0 then
+        return nil
+    end
+    table.sort(hits)
+    for _, k in ipairs(hits) do
+        data[k] = nil
+    end
+    return table.concat(hits, ", ")
+end
+
 -- Iterate lines, yielding the line plus its start offset and the offset just
 -- past its newline, so the caller can slice the original text exactly.
 local function lines(text)
@@ -79,17 +108,22 @@ function M.parse(text)
         return {}, body, nil
     end
 
-    local ok_lyaml, lyaml = pcall(require, "lyaml")
-    if not ok_lyaml then
-        return nil, body, "lyaml is not installed; ignoring the YAML frontmatter"
+    local ok_yaml, yaml = pcall(require, "tinyyaml")
+    if not ok_yaml then
+        return nil, body, "tinyyaml is not installed; ignoring the YAML frontmatter"
     end
-    local ok, data = pcall(lyaml.load, block)
+    local ok, data = pcall(yaml.parse, block)
     if not ok then
         return nil, body, "YAML frontmatter did not parse: " .. tostring(data)
     end
     if type(data) ~= "table" then
         return nil, body, "YAML frontmatter is not a mapping; ignoring it"
     end
+    local aliased = strip_unresolved_aliases(data)
+    if aliased then
+        return data, body,
+            "YAML anchors/aliases are not supported; ignoring: " .. aliased
+    end
     return data, body, nil
 end