Implements the per-window concurrency view per AACE RP 29R-03
        §3.3.I (apportionment) and §4.2 (concurrency). Where
        ``forensic_windows_analysis`` answers "how many days does each
        party own across the whole project?", this tool answers "how did
        each window distribute its shift across the parties?" — useful
        when defending or attacking concurrency findings on a
        window-by-window basis.

        CPP conservation check, per the AACE 29R-03 §3.3.E.13
        requirement that the summed per-period net impacts equal the
        difference between the first schedule update and the last
        schedule update used in the evaluation: the sum of per-party
        column totals equals the sum of per-window completion shifts
        within ±1 day of rounding. The column-total definition is this
        tool's own bookkeeping, not an AACE rule. The ``conservation_check`` field on
        the response reflects this; ``conservation_diff_days`` carries
        the exact gap.

        IMPORTANT — conservation is NOT attribution. ``conservation_check``
        can be True (the columns sum to the grand total) even when 100% of
        the shift lands in the Unattributed column, i.e. no party owns any
        of the drift. Read ``unattributed_share_pct`` and
        ``high_unattributed_share_warning`` to know whether a meaningful
        apportionment actually occurred. A fully-unattributed matrix
        conserves perfectly but attributes nothing — never present its
        green conservation check as a validated apportionment.

        Use this tool when you only need the matrix view; use
        ``forensic_windows_analysis`` for the full claim.

        Args:
            schedules: chronologically ordered list of dicts — the SAME
                shape ``forensic_windows_analysis`` accepts. Each dict
                carries ``label`` (optional) and EXACTLY ONE of
                ``xer_content`` (full XER text, hosted/remote use) or
                ``xer_path`` (server-side path, local use). This is the
                preferred input for hosted/remote clients.
            xer_paths: legacy chronologically ordered list of server-side
                XER file paths (local-server use).
            xer_contents: legacy chronologically ordered list of XER text
                contents. Each element is the full text of one XER.
            Supply EXACTLY ONE of schedules / xer_paths / xer_contents
            (lists must have at least 2 entries either way).

        Returns:
            {
              "parties": ["Owner", "Contractor", "Concurrent",
                          "Force Majeure", "Unattributed"],
              # Unit for every shift_* field and the grand totals. Always
              # "working_days" — the matrix measures the completion shift
              # in working days (Dana default). The *_calendar_days twins
              # express the SAME shift in calendar days so an unlabeled
              # "11" can never be mistaken for the 15-calendar-day value.
              "shift_unit": "working_days",
              "rows": [{ "window_label", "period_start", "period_end",
                         # shift_days == shift_workdays (working days,
                         # legacy alias). shift_calendar_days is the same
                         # shift in calendar days; shift_basis names the
                         # finish driver the shift was measured on.
                         "shift_days", "shift_unit", "shift_workdays",
                         "shift_calendar_days", "shift_basis",
                         "parties": {party: days},
                         "cascade_inferred": bool }, ...],
              "column_totals": {party: days},
              "grand_total_shift": int,          # working days (legacy)
              "grand_total_shift_workdays": int,
              "grand_total_shift_calendar_days": int | None,
              "conservation_check": bool,
              "conservation_diff_days": int,
              # Disambiguates "conserved AND attributed" from "conserved
              # but entirely Unattributed". unattributed_share_pct is
              # |Unattributed| / sum|shift| as a percent; the warning
              # flips True when that share is dominant (>= 50%).
              "unattributed_share_pct": float,
              "high_unattributed_share_warning": bool,
              "standard": "AACE RP 29R-03 §3.3.I (apportionment) · §4.2 (concurrency)"
            }