fix(provider): a value ending in a backslash no longer vanishes

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser

[Chemaclass]

🤔 Background

Related #1134

A provider value ending in a lone backslash reached the test unset, so the
test ran against nothing:

provider emits	before	after
C:\	<unset>	C:

💡 Root cause

An odd run of trailing backslashes escapes the ) that the parser's fast path
appends, so eval sees args=(C:\) — unterminated. That is a syntax error,
not a failed command, and a syntax error inside eval kills the enclosing
command substitution. exec.sh calls the parser as
<<<"$(parse_data_provider_args "$data")", so the substitution returned nothing.

It is also why the parser looked correct in isolation — writing to a file it
prints C: fine; only the in-situ call through $( ) loses it.

💡 Changes

• Detect the odd trailing backslash and skip the eval path; the fallback parser already handles the input
• Test in tests/functional/provider_test.sh, verified to fail against the unfixed parser