Build - Scoping & Estimation (Internal)

Never client-facing. The unit each step is sized in, its S/M/L/XL bands, and the role mix - one section per step, in step order. Hours per step per tier are in the effort model; the tier model and prices in productisation.md. Bands and tiers are defined in depth.md.

4.1 Engineering Foundations

Line: near-fixed ~14 hrs (Acorn-based) - repo 6, hosting and CI/CD 4, architecture and stack ADRs 4. This is setup, and setup is a small part of engineering: the bulk of the build sits in the master UI (4.3). The split between this line and the master UI is argued rather than measured - see calibration flag 6 in the effort model for what needs confirming. Enterprise constraints (security/compliance reviews, client-side infrastructure, unusual environments) price as scoped additions from the Cornerstone's technical specification, not absorbed.

Role mix: engineer-led; lead engineer confirms architecture against the Cornerstone.

4.2 Frontend Development

Lines: templates ~8 hrs · variants ~2 hrs · tools 10–20 hrs by screens/states - all × the band multiplier. Counts come from the Cornerstone's surface inventory; bespoke functional features from the scope table price as tool-scale allowances. See the effort model.

Role mix: engineering mids build; lead engineer reviews per batch (with Mira on every pull request).

4.3 CMS & Data Layer

Line: ~4 hrs per content type, band-free. Counts come from the Cornerstone's content model. Highly relational models (XL) price from the actual relationships, not the type count alone.

Role mix: engineer-led; lead engineer owns the schema review.

4.4 Integrations & Functionality

Line: per integration by kind and volatility - standard, playbook-covered (forms, analytics, search) ~8 hrs; business systems and volatile/custom APIs ~15 hrs plus the 2.2 risk allowance. Bespoke functional features price as tool-scale allowances from the scope table. Counts come from the Cornerstone's integration map.

Role mix: engineer-led; lead engineer owns volatile-API risk.

4.5 Stabilisation & Internal QA

No separate line. Stabilisation and internal QA are inside the build line rates - the calibration actuals were logged that way (fix-as-you-go plus the formal pass, within build hours). If future line-level capture shows the alpha pass growing beyond what the rates carry, split it out then - see the effort model calibration flags.

Role mix: whole build team; lead engineer owns the alpha gate.