Unhandled `treesit-query-error` in `pi-coding-agent--markdown-visible-string` crashes table rendering mid-stream

[DevGiuDev]

When pi-coding-agent renders a streaming response containing a Markdown table with cells that include inline markup (e.g. 🛒 **Marketplace**), it calls font-lock-ensure on a temporary md-ts-mode buffer. If md-ts-mode's tree-sitter font-lock rules throw a treesit-query-error, the exception propagates uncaught up through the streaming render pipeline, breaking the rest of the response display.

The user sees the response truncated mid-table, with subsequent content missing from the chat buffer.

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Environment

Emacs	30.2
pi-coding-agent	20260405.21
md-ts-mode	20260309.11
tree-sitter system library	0.26.8
Model	glm-5.1 via ZAI (openai-completions provider)

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Steps to Reproduce

1. Start a new pi-coding-agent chat session with a model that produces rich Markdown tables (e.g. glm-5.1 via ZAI).
2. Send a prompt that triggers a response containing a table with bold text or emoji in cells:

Search for a file in ~/dev/myproject/, read it, and summarize it.

3. Observe the response is cut off mid-table in the chat buffer.
4. Check *Messages* for the error — with debug-on-error t the full backtrace is:

Debugger entered--Lisp error: (treesit-query-error "Syntax error at" 136
  "(block_quote) @md-ts-block-quote ..."
  "Debug the query with `treesit-query-validate'")
  treesit--font-lock-fontify-region-1(...)
  treesit-font-lock-fontify-region(1 18 nil)
  font-lock-ensure()
  pi-coding-agent--markdown-visible-string("🛒 **Marketplace**")
  pi-coding-agent--table-display-groups(...)
  pi-coding-agent--decorate-table(...)
  pi-coding-agent--maybe-decorate-streaming-table()
  pi-coding-agent--display-message-delta(" |\n")
  pi-coding-agent--handle-display-event(...)

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Root Cause

pi-coding-agent--markdown-visible-string (in pi-coding-agent-table.el) creates a persistent buffer in md-ts-mode and calls font-lock-ensure to extract the visible text of a table cell:

(defun pi-coding-agent--markdown-visible-string (markdown)
  ...
  (with-current-buffer (pi-coding-agent--visible-string-buffer)
    (let ((inhibit-read-only t))
      (erase-buffer)
      (insert markdown))
    (font-lock-ensure)          ; <-- can throw treesit-query-error
    (pi-coding-agent--visible-text (point-min) (point-max))))

font-lock-ensure is called without any error handling. When md-ts-mode's paragraph/prepend tree-sitter query fails at the C level (a known incompatibility between Emacs 30 treesit.c generating #match and tree-sitter 0.25+ requiring #match?), the exception escapes into pi-coding-agent--display-message-delta, silently aborting the render of the current and all subsequent streaming deltas.

Note: the same treesit-query-error also appears as Error during redisplay: (jit-lock-function ...) in the main chat buffer — that is a separate manifestation of the same md-ts-mode query bug (reported independently at https://github.com/dnouri/md-ts-mode/issues/XXX).

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Proposed Fix

Wrap font-lock-ensure in a condition-case and fall back to returning the raw markdown string on error. This makes the function resilient to any font-lock failure, not just this specific md-ts-mode query issue:

(defun pi-coding-agent--markdown-visible-string (markdown)
  ...
  (with-current-buffer (pi-coding-agent--visible-string-buffer)
    (let ((inhibit-read-only t))
      (erase-buffer)
      (insert markdown))
    ;; Guard against treesit-query-error or other font-lock failures
    ;; (e.g. md-ts-mode query incompatibility with tree-sitter 0.25+).
    ;; On failure, fall back to the raw markdown string.
    (condition-case _err
        (font-lock-ensure)
      (error nil))
    (pi-coding-agent--visible-text (point-min) (point-max))))

The fallback is safe: pi-coding-agent--visible-text still returns a reasonable string (the raw markdown with delimiters visible), which is better than crashing the render pipeline entirely.

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Additional Notes

• The bug is not model-specific in principle, but in practice it is triggered more frequently by models like glm-5.1 (ZAI) that tend to produce tables with rich inline markup (bold + emoji) in cells. Models that generate plain-text table cells never hit this code path.
• The treesit-query-error only fires when md-ts-mode is the active mode in the fontification buffer and the installed tree-sitter library is 0.25+. Users on older tree-sitter versions are unaffected.
• A fix to md-ts-mode itself (removing the broken :match predicate) eliminates the root cause entirely. This defensive fix in pi-coding-agent is recommended regardless, as it protects against any future font-lock errors from any mode used in the fontification buffer.