v2 pre-flip: replace hardcoded raw/steps/summary column literals in utils and filters

[jepegit]

Context

Phase-3 flip prerequisite (native-headers plan Phase 0, item 2; hardcoded-column-headers-report §8 priority 2 + §9). Audited 2026-07-17 with .issueflows/00-tools/scan_hardcoded_headers.py; remaining HeadersNormal / HeadersStepTable / HeadersSummary findings:

File	Findings
cellpy/utils/plotutils.py	26
cellpy/utils/helpers.py	~20 (non-journal subset)
cellpy/utils/ocv_rlx.py	8
cellpy/filters/summary.py	2 (the default rate_columns=("charge_c_rate", "discharge_c_rate") tuple — §9.2)

(ocv_rlx was ~25 and plotutils ~40 at report time — partially done already; this finishes the pass.)

Work

Mechanical 1:1 onto the canonical header objects (get_headers_normal() / get_headers_step_table() / get_headers_summary()), same pattern as the sibling journal issue. Out of scope: literals the scan attributes to the capacity-curve frame ("capacity", "voltage", "cycle", "direction", "q", "v", "dq") in easyplot/ica/collectors/plotutils — those belong to the CurveCols adoption issue, since fixing consumers before the producer just moves the hard-coding around (report §5).

Acceptance

• Scan tool reports zero non-curve findings for the files above
• Full suite green

🤖 Generated with Claude Code

[jepegit]

Resolved by splitting into its correctly-scoped parts (discovered during implementation — the string-matching scan mis-attributed most hits):

• Done — the genuinely in-scope raw/steps/summary header literals: utils/helpers.py string-keyed lookups → attribute access, and filters/summary.py's rate_columns default resolved from HeadersSummary. Shipped in Header-object attributes for column lookups in helpers and filters (#538) #542 (postfix/specific *_gravimetric/areal_* columns intentionally kept as string-key composition per report §8-5).
• Re-routed to v2 pre-flip: adopt cellpycore CurveCols as the canonical capacity-curve schema #540 — plotutils.py's "cycle"/"voltage"/"direction" hits are get_cap curve-frame columns, not raw/steps/summary; they can only be migrated once the CurveCols compat surface is decided.
• Re-routed to v2 pre-flip: replace hardcoded step-type string literals with cellpycore StepType constants #543 — ocv_rlx.py's "charge"/"discharge"/"ir" hits are step-type values / dict keys, which need the StepType vocabulary, not header attributes.

Closing as completed; the two follow-ups (#540, #543) carry the remainder.