test(web): align system-prompt pins with the reference guidance

The pinned prompts were recorded on master before this branch's
file-reference guidance rewrite; refresh them so the pin carries the
directory-aware wording the assembly now produces.

snapshots/web/code-mode-round/system-prompt.expected.md

@@ -8,7 +8,7 @@ You are a coding agent powered by the deepseek-v4-flash model. Your working dire
 
 `run_code` is the only tool you can call directly — a tool call naming any other tool fails. Reach every tool the SDK declares below from inside the program.
 
-Paths prefixed with @ are files explicitly referenced by the user. Use the read tool when their contents are needed; do not claim to have inspected a file before reading it.
+Tokens prefixed with @ are workspace paths the user explicitly referenced, relative to the workspace root. A trailing slash marks a directory: list it when its contents matter. Anything else is a file: use the read tool when its contents are needed, and do not claim to have inspected it before reading. @"..." quotes a path containing spaces.
 
 Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
 

snapshots/web/cordis-tool-round/system-prompt.expected.md

@@ -6,7 +6,7 @@ You are interacting with the user through the DeepSeek Harness Web GUI at {{webU
 
 You are a coding agent powered by the deepseek-v4-flash model. Your working directory is {{cwd}}.
 
-Paths prefixed with @ are files explicitly referenced by the user. Use the read tool when their contents are needed; do not claim to have inspected a file before reading it.
+Tokens prefixed with @ are workspace paths the user explicitly referenced, relative to the workspace root. A trailing slash marks a directory: list it when its contents matter. Anything else is a file: use the read tool when its contents are needed, and do not claim to have inspected it before reading. @"..." quotes a path containing spaces.
 
 Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.
 

snapshots/web/fresh-round-trip/system-prompt.expected.md

@@ -6,7 +6,7 @@ You are interacting with the user through the DeepSeek Harness Web GUI at {{webU
 
 You are a coding agent powered by the deepseek-v4-flash model. Your working directory is {{cwd}}.
 
-Paths prefixed with @ are files explicitly referenced by the user. Use the read tool when their contents are needed; do not claim to have inspected a file before reading it.
+Tokens prefixed with @ are workspace paths the user explicitly referenced, relative to the workspace root. A trailing slash marks a directory: list it when its contents matter. Anything else is a file: use the read tool when its contents are needed, and do not claim to have inspected it before reading. @"..." quotes a path containing spaces.
 
 Use the read tool — not shell commands like cat — to inspect text files. Results include line numbers. Use offset and limit to continue reading large files.