feat(trial): add BF16 to quant harness; fix igllama json_mode crash

- trial_quant.zig: add 2B-BF16 and 9B-BF16 to QUANT_MODELS; covers
  Q4/Q5/Q6/Q8/BF16 precision curve for both weight classes
- trial_quant.zig: change response_format from json_object to text;
  igllama grammar sampler (llama_sampler_init_grammar) crashes during
  generation for 2B+ vocab sizes — system prompt alone is sufficient
  for constrained JSON output at 2B+
- trial_quant.zig: remove --mlock spawn flag (optimization, not required)
- igllama v0.3.10: fix streaming handler use-after-free in json_mode;
  loadGrammar + defer free → direct JSON_GRAMMAR comptime const
- LICENSE: add MIT license file
- CHANGELOG.md: v0.2.7 entry
- CLAUDE.md: version 0.2.7, roadmap items 14-15
- showcase.smd: document igllama json_mode crash finding, update
  engineering requirements, expand trial task suite to T01-T17,
  update framework version to v0.2.7/v0.3.10

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: bkataru

CHANGELOG.md

@@ -2,6 +2,17 @@
 
 All notable changes to the **powerglide** project will be documented in this file.
 
+## [0.2.7] - 2026-03-04
+
+### Added
+- **BF16 trials in `trial_quant.zig`** — `2B-BF16` and `9B-BF16` added to `QUANT_MODELS`; harness now covers the full Q4/Q5/Q6/Q8/BF16 precision curve for both weight classes
+
+### Fixed
+- **igllama v0.3.10 — streaming json_mode use-after-free** — streaming handler called `loadGrammar(allocator, "json")` then `defer allocator.free(gs)` inside the if-block, freeing the grammar string while the sampler still held a pointer. Replaced with direct `JSON_GRAMMAR` comptime constant (matching the non-streaming handler); no allocation, no lifetime issue. igllama no longer crashes when `response_format: {"type":"json_object"}` is sent on a streaming endpoint.
+
+### Changed
+- **CLAUDE.md** — version `0.2.7`; roadmap item 14–15 updated
+
 ## [0.2.6] - 2026-03-04
 
 ### Added

CLAUDE.md

@@ -55,11 +55,11 @@ Start with: `igllama api <model> --port <N> --no-think --max-tokens 512 --thread
 - `OpenAIClient.json_mode = true` → forces `response_format: {"type":"json_object"}` for constrained output
 - Doctor scans `:8090–8099` automatically
 - Trial harness: `zig build trial` — runs T01–T17 × all 4 endpoints
-- Quant harness: `zig build trial-quant` — runs T01–T13 × Q4/Q5/Q6/Q8 on 2B and 9B (sequential on :8090)
+- Quant harness: `zig build trial-quant` — runs T01–T13 × Q4/Q5/Q6/Q8/BF16 on 2B and 9B (sequential on :8090)
 
 ## Current Version
 
-`0.2.6` — 195/195 tests passing, 0 leaks.
+`0.2.7` — 195/195 tests passing, 0 leaks.
 
 ## Roadmap
 
@@ -73,9 +73,8 @@ Start with: `igllama api <model> --port <N> --no-think --max-tokens 512 --thread
 8. ✅ igllama integration — local Qwen3.5 agents, json_mode, port scanning
 9. ✅ Session summary output on `powerglide run` completion
 10. ✅ Showcase page — dogfooding case studies: full Qwen3.5 lineup (0.8B/2B/4B/9B)
-11. ✅ Zig trial harness (`examples/trial.zig`) — T01–T13 × 4 weight classes at Q4/Q8
-12. ✅ igllama json_mode patch — GBNF grammar constraint via `response_format` (v0.3.9)
+11. ✅ Zig trial harness (`examples/trial.zig`) — T01–T17 × 4 weight classes at Q4/Q8
+12. ✅ igllama json_mode fix — streaming handler use-after-free (v0.3.10)
 13. ✅ Security: grep/glob tools use direct argv (no shell interpolation of user input)
-14. ✅ BF16 analysis — confirmed capacity-limited, not precision-limited; removed BF16 harness
-15. ✅ Expanded trial tasks T14–T17 (code gen, JSON round-trip, error recovery, multi-source)
-16. ✅ Quantization sensitivity harness (`examples/trial_quant.zig`) — Q4/Q5/Q6/Q8 on 2B+9B
+14. ✅ Quantization sensitivity harness (`examples/trial_quant.zig`) — Q4/Q5/Q6/Q8/BF16 on 2B+9B
+15. ✅ BF16 precision trials added to quant harness — full precision curve documented in showcase

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 bkataru
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.