feat(server): plain-text call:<verb>{} tool parsing (Gemma4)

[easel]

Summary

Adds plain-text call:<verb>{...} tool-call parsing for Gemma4 emissions to the server's tool_parser. The parser also tolerates the `_call: tokenizer artifact prefix and renders Anthropic-style tool_use / tool_result blocks. Changes are localized to tool_parser.{cpp,h}; no streaming-path edits in this PR.

Files

• server/src/server/tool_parser.cpp — parser implementation for the call:<verb>{...} form (+192 LOC)
• server/src/server/tool_parser.h — small surface additions for the new branch
• server/test/test_server_unit.cpp — unit tests covering the new parser branches (+172 LOC)

Single commit: feat(server): plain-text call:<verb>{} tool parsing (Gemma4).

Dependencies

None — this PR is independent of the other split PRs.

Note: while this PR's code is self-contained, the server target itself cross-references symbols introduced/moved by sibling PRs (#336 layer split, #338 pflash drafter, #339 soft-close, #341 thinking-control), so building the server CMake target from this branch in isolation will not produce a complete binary. The parser additions themselves do not depend on any sibling PR.

Test plan

• test_server_unit (the new branches added in this PR) passes locally
• Smoke a Gemma4 trace emitting call:<verb>{...} (and the `_call: variant) end-to-end once the full server stack is assembled with sibling PRs
• Confirm no regressions in existing tool_parser branches (JSON tool_use path, etc.)

Note: server PRs in this split cannot be validated as a runnable binary standalone due to CMake cross-references with the other split PRs; the unit tests added here are the only standalone validation.

[cubic-dev-ai]

1 issue found across 3 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="server/src/server/tool_parser.cpp">

<violation number="1" location="server/src/server/tool_parser.cpp:582">
P1: Disallowed `call:<verb>{...}` spans are not shadowed, allowing pattern 6 to emit spurious inner tool calls.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P1: Disallowed call:<verb>{...} spans are not shadowed, allowing pattern 6 to emit spurious inner tool calls.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At server/src/server/tool_parser.cpp, line 582:

<comment>Disallowed `call:<verb>{...}` spans are not shadowed, allowing pattern 6 to emit spurious inner tool calls.</comment>

<file context>
@@ -397,7 +545,45 @@ ToolParseResult parse_tool_calls(const std::string & text, const json & tools) {
+            if (colon != std::string::npos) verb = verb.substr(colon + 1);
+            if (verb.empty()) continue;
+
+            add_call(verb, args, call_start, brace_close);
+        }
+    }
</file context>

Suggested change

	add_call(verb, args, call_start, brace_close);
	if (tool_allowed(tools, verb)) {
	add_call(verb, args, call_start, brace_close);
	} else {
	removals.push_back({call_start, brace_close});
	}