[lyingbug]

Description

Some OpenAI-compatible endpoints return a DSML function_calls block in content with finish_reason=stop. The agent then displays protocol markup and stops instead of invoking tools. Recover complete trailing DSML blocks in both streaming and non-streaming completions, using the tools enabled by the current request.

• Preserve plain-text preambles and handle markers split across stream chunks, including full-width and ASCII bars.
• Leave Markdown examples, undeclared or disabled tools, incomplete envelopes, malformed parameters, and abnormal completion endings unchanged. Respect named tool choices and disabled parallel calls.
• Prefer native tool_calls when both representations are present, avoiding duplicate execution.
• Preserve JSON integers and decimals without converting them through float64.

Recovery is conservative: ambiguous or partially parsed content remains text. No configuration or public API changes.

Type of Change

• 🐛 Bug fix
• 🧪 Test

Related Issue

Related to #2798, which addresses leaked DSML with rejection and retry.

Testing

• 37 response scenarios, each exercised through both Chat and ChatStream using local HTTP/SSE fixtures.
• Confirmed the quoted-example, malformed-parameter, duplicate-call, and integer-precision regressions fail against the original implementation in both response modes, then pass with this fix.
• go test ./internal/models/... ./internal/agent/...
• go vet and go test over all 148 CI application packages, excluding /docreader/ as in app.yml.
• Server build: go build -o <temporary-directory>/server ./cmd/server.
• golangci-lint run --new-from-rev=github_public/main ./... — 0 issues.
• git diff --check github_public/main...HEAD

Checklist

• Diff whitespace check passes
• Changed Go files are formatted
• Targeted and application tests pass
• Diff-scoped lint passes
• Broader checks and their scope are recorded above
• Self-reviewed the code
• Added regression coverage
• Documentation considered; no configuration or public API documentation changes needed
• No breaking changes

Screenshots / Recordings

Not applicable; backend-only change.