[Duang777]

Goal And Delivered Outcome

• Outcome basis / optional anchor: self-found core defect. No public issue; the request in this PR is the basis.
• Goal/source and gap: load_index_snapshot in loopx/history.py decoded each run-index line with a strict bytes.decode("utf-8"), but the index is written with ensure_ascii=False, so an interrupted append can end inside a multibyte character. The append helpers already repair the missing newline after a torn tail, so later rows keep landing behind the damaged one.
• Observable before → after, with the validation row that proves it: One such row raised UnicodeDecodeError from every reader of that index: history and status collection, the Todo and refresh-state readers and the readback in write_compact_runtime_projection. After: the row is counted in raw_count / invalid_count like an unparseable JSON row and the intact rows are returned; the digest still covers the original bytes. Rows: regression_parity, unit.
• Issue/task and intended base: none. Base is main at 7bb1b01.

Author Declaration

• Written by: agent, Claude Sonnet 5.5, for @Duang777

Implemented against

• Specification and revision: no written specification; the request in this PR is the basis.
• Criteria:

Criterion (spec clause)	Disposition	Symbol / path	Test or command
A damaged row must not take down every reader of the index	implemented	load_index_snapshot in loopx/history.py	tests/control_plane/test_run_index_jsonl_framing.py::test_history_read_skips_a_row_torn_inside_a_multibyte_character

• Self-check before submission: reproduced the defect on the unfixed code, then confirmed the new test fails before and passes after. Did not run the full suite or CI-equivalent gates locally. Also tried the same tolerance in slot_accounting._load_goal_run_index_records and dropped it: the real settlement readback already fails closed there.

Scope And Continuation

• Completed scope and remaining work: complete within this scope. A torn row is skipped and counted, not repaired.
• Slice boundary / successor: N/A, one independent defect.

Validation

• Tested revision: e2202a3eef43004fc8aeb2cf06bdfe5d61c5f77f for the diff; local runs used a working tree whose touched files were blob-identical to main 7bb1b01 before the change (the touched history.py hunk was re-applied to the current main file; the replaced line is unchanged upstream).
• Run state: finished
• Input classes: synthetic

Check kind	Result	Public-safe evidence / limitation
regression_parity	passed	The new test fails on the unfixed code with UnicodeDecodeError and passes with the fix; write_compact_runtime_projection also stops crashing.
unit	passed	test_run_index_jsonl_framing.py 18/18; ruff check clean on both touched files.
unit	failed	The history and quota-settlement test files showed 14 failures both with and without this change on the stale local tree (missing loopx.chat_event_cache); not re-run on main.

• Coverage and gaps: The 14 local failures are an artifact of the local tree and need confirming against CI on this head.

Frontend / Visual Evidence

• UI impact: none

Type of Change

• Bug fix
• New feature
• Breaking change
• Refactoring (no functional changes)
• Documentation update
• Test update

LoopX Area

• Control plane (goals, todos, quota, scheduler, registry, runtime)
• Benchmark boundary (adapters, runners, verifiers, scoring, evidence)
• Capability or extension (providers, adapters, skills)
• Public docs or presentation surface (README, protocols, dashboard)
• Build, packaging, installer, or CI
• Host or runtime integration

Technical Direction

• Direction / acceptance reference, when applicable: Core control-plane hardening.

Shared-authority RFC fixture impact

N/A

Boundary Checklist

• Neither the diff nor this PR body/comments/attachments disclose private state, credentials, raw traces or verifier output, internal links, or local machine paths (including .loopx/, .codex/goals/, and live ACTIVE_GOAL_STATE.md).
• I did not duplicate maintainer-owned benchmark work unless a maintainer split out a public issue for it.
• I kept the change scoped to the linked issue/task.
• Existing English/Chinese RFC pairs (including ledger entries) both have a diff, and the local premerge check passes, or no paired RFC changed. No RFC changed.
• I completed the visual evidence section for UI changes, or marked UI impact none.
• Every commit includes a DCO Signed-off-by trailer (git commit -s).

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