Fix $-pattern corruption of user_config values in replaceVariables#259
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Fix $-pattern corruption of user_config values in replaceVariables#259aosmcleod wants to merge 1 commit into
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String.prototype.replace treats $ sequences ($&, $$, $`, $', $n) in the replacement string as special patterns, so any user_config value containing a $ — e.g. a password with $& in it — was silently corrupted before being injected into mcp_config. The server then received wrong credentials. Pass a replacement function so the value is inserted verbatim. Adds a regression test covering $&, $$ and $n in a substituted value.
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Problem
replaceVariablessubstitutes${user_config.*}placeholders usingString.prototype.replace(pattern, replacement), wherereplacementis the raw user_config value. JavaScript treats$sequences in the replacement string as special patterns ($$,$&,$`,$',$n), so any user_config value containing a$is silently corrupted before it reaches the MCP server's environment.In practice this caused an MCP server to receive a mangled password and fail authentication with a generic 401, even though the user's credentials were correct. The password contained
$&, which expands to the entire matched placeholder.Fixes #258.
Fix
Pass a replacement function to
replace, which disables special-pattern interpretation and inserts the value verbatim:The array-expansion path already uses
push(replacement)directly and was unaffected.Test
Adds a regression test asserting that a value containing
$&,$$and$nis substituted literally. Verified that the test fails against the oldreplace(pattern, replacement)form and passes with the fix.yarn lintandyarn testboth pass.